Ok, here goes.
Ability score placement:
Strength and charisma are your top most important stats, followed by dex and con. Wis takes last place, leaving int in fifth.
Str 17 +4 levels
Dex 16
Con 16
Int 14
Wis 13
Cha 16 +4 levels
Bard side:
Level 1: Bard
This is here rather than with the rest to make best use of level 1 skill point multiplication.
Levels 2 and 3: Paladin of Freedom (http://www.d20srd.org/srd/variant/classes/variantCharacterClasses.htm#paladinofFreedomClassF eatures)
The chaotic good version of Paladin. You're going to have a nice high charisma score, and this will make good use of that by applying it to all saves. That's pretty much the whole reason for taking it in this build. The other class features you can write down, but you don't really need to pay attention to them.
Levels 4 - 7: Bard 2-5
More Bard. By the time you finish this, you need 4 ranks of Diplomacy, 4 of Intimidate, and 10 of Perform for prerequisites.
Levels 8-10: Virtuoso 1-3
This gets you to level 7 Bard casting, just enough to get 3rd level spells and qualify for Sublime Chord. Virtuoso also advances Inspire Courage, the only bard song you really care about, and gives some nifty other songs.
At this point, you need Knowledge (Arcana) 13, Listen 13, Perform 10, Profession (Astrologer) 6, and Spellcraft 6.
Level 11: Sublime Chord
This supercharges your casting. You'll be at 8th level spells, with access to the sor/wiz list, thanks to this.
Levels 12-18: Virtuoso 4-10
Have these all advance Sublime Chord instead of Bard. The result is high Inspire Courage, great casting, and all the Virtuoso songs.
End result:
Spells per day and known as Bard 7 and Sublime Chord 8 (caster level 15 for each)
Inspire Courage as Bard 15 (so +3, but we'll adjust this later for more)
Bardic Music 15 times per day
Bardic Lore as Bard 6
Charisma to all saves
All Virtuoso songs
There are some miscellaneous other things, but they aren't important.
Crusader side:
Levels 1-13: Crusader
Aside from the maneuver stuff, which I'll go over in detail later, the important things here are:
20 points of delayed damage (which gives you +4 attack and damage when it's full)
1/day reroll a save with no action cost
Mettle
You need a bunch of feats here for prereqs, along with some skills.
Levels 14-18: Master of Nine
The really important part of why I'm recommending this is the extra maneuvers readied. Why this is so important will become apparent when I explain maneuvers.
Dual Stance, Counter Stance, and Mastery of Nine are also very good.
Skills:
14 int plus the special 2 from house rules means base +4 skill points. We're going to have at least 4 base at all levels, and 6 for most, so that's 8 to 10 skills worth.
You have important prerequisites in:
Spellcraft
Knowledge (Arcana)
Listen
Perform
Diplomacy
Intimidate
4 discipline key skills
Profession (Astrologer)
Concentration
Aside from the last two, where you only need 5 or 6 and more serves little purpose, you might as well max them out. Diplo and Intimidate can serve as two of the discipline skills, let's go with Tumble and Sense Motive for the other two (your other options are Hide, Balance, Jump, and Concentration - normally I'd take Concentration, but you'll be using Perform for everything you need it for thanks to Melodic Casting).
So, primary skills are: Spellcraft, Knowledge (Arcana), Listen, Perform, Diplomacy, Intimidate, Tumble, Sense Motive.
Level by level:
Level 1: Bard is 6, so 10 maxed skills. All primary skills are in-class for either Bard or Crusader, so max them all at 4, and we have 8 points left. Dump 4 in Profession (Astrologer) to work towards that prereq, and 4 in Concentration for that one.
Level 2 and 3: Paladin only has 2, so Crusader's 4 is what we get. 8 points per level. Sadly, only Diplo, Intim, and Sense Motive of our main 8 are in-class for these levels. Spend 4 per level on those 3 plus Profession (Astrologer), bringing it to the 6 needed for the prereq. The other 4 points per level can keep 2 of the other skills at max.
Levels 4-7: Back to Bard with 6+4, and everything is in-class. 8 skills to push, 3 of them are 2 points behind. We have 2 spare skill points per level, 4 levels, 8 spare points, 3 * 2 = 6 needed to bring the falling-behind skills back up to max. All main skills are maxed again, the profession prereq is already met, and we have 2 points left over. 1 of those brings Concentration to the 5 needed for a prereq, the other can go wherever.
Levels 8-10: Virtuoso has 6 base just like Bard, but is missing Knowledge (Arcana) and Listen as class skills. It's also missing Sense Motive, but one of your Martial Study feats makes that permanently in-class regardless. 8 skills, 2 of them cross-class, takes 10 points per level to keep maxed, which is exactly what we have.
Level 11: Sublime Chord gets Knowledge and Listen in class, but drops Tumble in exchange. However, one of your Martial Study feats makes Tumble permanently a class skill regardless, so it doesn't matter. It also drops to 4 skill points, so net no change - we still have exactly enough to continue maxing things out.
Levels 12-13: Virtuoso//Crusader again, keep maxing the mains.
Levels 14-18: Virtuoso//Master of Nine. Skills-wise, this works out the same as Virtuoso//Crusader.
Net result: All 8 main skills are maxed at 21 ranks each. Profession (Astrologer) is at 6 ranks as needed for prereq, and Concentration is at 5 as needed for another prereq. You have 1 spare point to put in whatever random thing strikes your fancy. Class skill restrictions for that are from level 7.
Feats:
Unfortunately, Master of Nine requires a ton of feats, especially for a Crusader. Fortunately, you have a ton of feats.
Level 1: Improved Unarmed Strike, Blind-Fight
Level 3: Adaptive Style, Dodge
Level 6: Improved Initiative, Martial Study (Counter Charge)
Level 9: Martial Study (Rapid Counter), Martial Study (Burning Blade)
Ok, that takes care of Master of Nine prereqs, and works towards prereqs for some excellent maneuvers later. You probably won't actually want to use the maneuvers gained by Martial Study here, but there aren't many options for maneuvers that don't require other maneuvers as prereqs.
I'll go into Adaptive Style and the maneuvers later, and the rest is core stuff you should be pretty familiar with.
Flaw (Frail): Dragontouched
Level 12: Song of the Heart, Melodic Casting
Level 15: Dragonfire Inspiration, Arcane Strike
Level 18: Extra Granted Maneuver, Somatic Weaponry
From here, we have:
Inspire Courage gets an extra +1
Spellcasting doesn't interrupt Inspire Courage
Inspire Courage can give +Xd6 fire damage instead of +X attack and damage. If you have time, you can spend two rounds getting both effects up.
Any time, drop a level X spell as a free action for +X attack and +Xd4 damage on all attacks for a round.
Your maneuvers refresh faster.
Having your hands full (with a weapon and shield) doesn't interfere with somatic spellcasting components.
Spells known:
Bard casting:
Level 0: You get 6. Detect Magic, Prestidigitation, and Light are hard to beat for utility. For the other 3, I'd go with Dancing Lights, Mage Hand, and Summon Instrument.
Level 1: You get 4. Inspirational Boost and Improvisation are excellent, take them. If you expect to be leading large armies at any point, Amplify could let your Inspire Courage and/or Dragonfire Inspiration reach more people. There are several good options for the remaining 1 or 2.
Level 2: You get 4. Bladeweave is incredible for gishes. Glitterdust is spectacular, as always. The rest I will leave to you.
Level 3: Only 2 for this. Wounding Whispers is a great defense, and Haste is a superb buff for the whole party. There are several other good choices, but that's what I'd go with.
Sublime Chord casting:
At this point, the sor/wiz list opens up in addition to the bard list.
Level 4: You get 4. Ruin Delver's Fortune and Sirine's Grace are top choices. Dimensional Anchor will prevent teleport-capable foes from fleeing, which is very likely to be relevant with demons and devils typically having at-will Greater Teleport. There are quite a few other good choices at this level, especially with access to both Bard and Sor/Wiz lists.
Level 5: You get 4. Greater Dispel Magic is important utility against spellcasting foes, and Bards get it a level lower than everyone else. Dragonsight gives some excellent perception abilities, and you can cast it in the morning to last all day. Greater Blink is a very powerful defensive buff, and can let you walk through walls. Wall of Stone can be a very versatile battlefield shaping/control spell.
Level 6: You get 4. Bards get Irresistible Dance at this level, which is great when your spell slots go up to sor/wiz heights. If detective-style investigative work is ever relevant, Hindsight is crazily good at that. Disintegrate has a lot of barrier removal potential (and I'd save it primarily for that, it's not so good as a damaging attack). In the same vein as Dimensional Anchor, Greater Anticipate Teleportation makes teleport-based ambushes suicidal against you (cast it in the morning, it lasts all day). Freezing Fog is a frankly ridiculous area disable spell unless your opponents have Freedom of Movement. Sadly, that makes 5 so you'll have to pick 1 to drop.
Level 7: You get 3. There are no Bard spells from this point on, so Sor/Wiz only. Elemental Body. Cast it in the morning, pick air, and enjoy your various immunities and perfect fly speed all day long. Spell Turning is superb anti-caster defense, and lasts a good 2 and a half hours at your level. Greater Teleport gives you ultimate long range mobility.
Level 8: You get 2. Greater Plane Shift, in case you have any extraplanar travel needs. There are a few good choices here, but I'd recommend Moment of Prescience - good for an "oh ****" situation, and doesn't take an in-combat action. I'd avoid Mind Blank, because its immunity applies to your Bardic Music buffs too.
Maneuvers:
First, a general explanation of how things work. You have a grand total of 22 maneuvers known - 11 from Crusader, 8 from Master of Nine, and 3 from Martial Study feats. 11 of those can be "readied" at any given time.
You also have 5 stances known. You can only use one stance at a time, but you can keep it active indefinitely for free, and you can switch which one is active as a swift action. Handling maneuvers is a bit more complicated.
Go here (http://www.wizards.com/default.asp?x=dnd/we/20061225a), download the relevant documents, print out the pages with your maneuvers on them, and cut them up to make maneuver cards. Select your 11, and make a miniature deck out of them.
At the start of combat, shuffle and draw 9 maneuvers from your deck (leaving only 2 not drawn). These maneuvers are your "granted" ones, which are available for use. When you use a maneuver, put it in a discard pile of "expended" maneuvers.
At the end of your turn, draw one new maneuver from the deck. This maneuver is now granted along with any remaining in your hand. If you can't draw a new maneuver because the deck is empty, shuffle all 11 cards together again, both granted and expended, and draw a new set of 9. Continue this cycle until combat ends.
If at any time you decide you really need a maneuver you didn't ready, your Adaptive Style feat allows you to spend a full round action to re-choose the set of 11 readied maneuvers. When you do this, treat it like the beginning of combat - shuffle them all and draw 9.
For learning maneuvers, in addition to the levels when you get new maneuvers known there is a swap mechanic at even-numbered Crusader levels. The swap is explicitly allowed to upgrade to higher level maneuvers, unlike the Sorcerer or Bard spell known swap, so it's important to track even when starting at high level. You can also select lower level maneuvers in place of higher level ones any time you want, and this is sometimes desirable to get something of a different nature than what's available at the highest level. Most maneuvers require that you already know a certain number of maneuvers from the same discipline, and this may also force you to learn lower level maneuvers in order to increase your prerequisite count.
I'm filling this out by starting with the highest level maneuvers I really want, then going down a chain of maneuvers with progressively lower prerequisite counts in the same discipline.
Diamond Mind:
Time Stands Still. Because who doesn't like full attacking twice in the same round? Level 9, prereq count 4.
Stance of Alacrity. Swift and immediate actions are precious for ToB characters, and you have a few swift or immediate spells competing for them too. This effectively gives you an extra one, usable only for counters. Level 8 stance, prereq count 3.
Quicksilver Motion. You are somewhat reliant on full attacks for best effect. This lets you move and still do that. Level 7, prereq count 3
Pearl of Black Doubt. Stance, +2 AC every time someone misses you, resets 1/round, here primarily for prereqs. Level 3, prereq count 1.
Diamond Defense. +18 to any save at no notice. Level 8, no prereq.
Rapid Counter. The best no-prereq maneuver I could find in this discipline at a level low enough for when you take Martial Study.
Setting Sun:
Fool's Strike. Negating an attack? Good. Hitting the attacker at the same time? Great. Getting to say "stop hitting yourself"? Priceless. Level 8, prereq count 3.
Mirrored Pursuit. Try to run away? You follow, even when it's not your turn. Level 5, prereq count 2.
Feigned Opening. Can make AoOs less bad, but here primarily for prereqs. Level 3, prereq count 1.
Counter Charge. Someone's charging you? Not any more. Level 1, no prereq.
Desert Wind:
Flashing Sun. Flurry-like attack with any weapon, and you get to add Mastery of Nine bonuses. For use when Time Stands Still is either not granted yet or already expended. Level 2, prereq count 1.
Burning Blade. 1d6+18 fire damage on all attacks for 1 round. With a hasted Time Stands Still, that can seriously add up, but unfortunately is severely reduced by fire resistance. Level 1, no prereq.
Devoted Spirit:
Strike of Righteous Vitality. Attack and get a Heal spell at the same time. Level 9, prereq count 3.
Shield Counter. Shield bash someone to cancel their attack. Level 7, prereq count 2.
Thicket of Blades. Stance, 5' steps don't work against you any more. Level 3, prereq count 1.
Martial Spirit. Stance, every time you hit you heal someone within 30' (possibly yourself, if you want) for 2. Level 1, no prereq.
White Raven:
Order Forged From Chaos. You spend a move action, and the whole party (yourself included) gets to move. Level 6, prereq count 2.
Covering Strike. A boost despite the name, anything you hit in the round you use it can't make AoOs for 3 rounds. Level 4, prereq count 1.
White Raven Tactics. Swift action, set an ally's initiative to 1 less than yours, letting them act immediately after you. Level 3, prereq count 1.
Leading the Charge. Stance, all allies within 60' get +18 damage on charge attacks. Level 1, no prereq.
Stone Dragon:
You need something from this to qualify for Master of Nine, but it's not particularly important what. The discipline as a whole is lackluster and handicapped by not being usable while flying.
By level gained:
Level 1: Swap, Swap, Swap, Swap, Swap, Martial Spirit
Level 2: <pick something> Leading the Charge
Level 3: <pick something>
Level 4: <pick something>
Level 5: White Raven Tactics
Level 6: (Counter Charge), <pick something>
Level 7: Covering Strike
Level 8: Thicket of Blades
Level 9: (Rapid Counter), (Burning Blade), <pick something>
Level 10: <pick something>
Level 11: <pick something>
Level 12: Order Forged From Chaos
Level 13: Shield Counter
Level 14: Flashing Sun, Feigned Opening
Level 15: Diamond Defense, Pearl of Black Doubt
Level 16: Quicksilver Motion, Mirrored Pursuit
Level 17: Stance of Alacrity, Fool's Strike
Level 18: Time Stands Still, Strike of Righteous Vitality
Stances:
Stance of Alacrity, Pearl of Black Doubt, Martial Spirit, Thicket of Blades, Leading the Charge
I recommend readying: White Raven Tactics, Burning Blade, Order Forged From Chaos, Shield Counter, Flashing Sun, Diamond Defense, Quicksilver Motion, Mirrored Pursuit, Fool's Strike, Time Stands Still, and Strike of Righteous Vitality.
Note: Without Master of Nine, that list would be half as long and would be much less flexible, being constrained to only the 3 Crusader disciplines.
If you know you'll be fighting highly fire resistant enemies, replace Burning Blade with Counter Charge.
You will usually want to be using Stance of Alacrity.
Major Equipment:
Vest of Legends (DMG2)
Badge of Valor (Magic Item Compendium)
Belt of Magnificence (Miniature's Handbook) +6. You benefit from enough ability scores that you might as well.
+5 Soulfire (Book of Exalted Deeds) Nimble (Magic Item Compendium) Mithril Breastplate
+5 large shield
One-handed magic weapon of choice.
Ring of Evasion
Ring of Freedom of Movement
Amulet of Natural Armor
Vest of Resistance
Banner of the Storm's Eye (Magic Item Compendium)
Ring of Protection is of debatable value - it's superseded by Sirine's Grace, but you may not always have time to cast that. In any case, you'd have to combine it with one of the other rings.
I'm sure there's plenty of other stuff, but that plus your spells handles most of the basics I think.
One nifty combo it has goes like this: swift action to use Quicksilver Motion. This gives you a bonus move action. Use that to use Order Forged From Chaos to move the entire party (including you) into flanking position. Now everyone gets to full attack on their turns without needing to spend movement getting in position first - except you, who gets to full attack twice with Time Stands Still. Oh, and all of those 8 attacks (10 if you have Haste up) get +8 attack and +8d4 damage from spending an 8th level slot on Arcane Strike and +2 attack and +5 damage from Mastery of Nine.
The Vest of Legends boosts your effective Bard level for Inspire Courage to 20, making it +4. Song of the Heart bumps that to +5. Cast Inspirational Boost before-hand and it's +6. Activate your Badge of Valor immediately after too, and it's +7.
You have both evasion and mettle, along with high saves thanks to Divine Grace applying your +8 charisma bonus. You can boost them further by casting Ruin Delver's Fortune to apply that +8 again as a luck bonus, and if you're really worried you can use Diamond Defense to add +18 on top. Pretty much, if it allows a save you will pass - and if you pass, you ignore it entirely even if it normally still has a reduced effect on a save.
And I need to go to bed soon. I'll be back on tomorrow evening to answer questions and explain the rest of the build's highlights, if other people don't beat me to it.