Any 3rd party sourcebooks so good I should automatically allow them in my games?

[cosmonuts]

I want to expand my horizons.

EDIT

Okay, I get I shouldn't automatically allow characters without review, or all the material from a book, but you know what I'm trying to say.

[Callin]

What system?

[cosmonuts]

D&D 3.5e, in an all splatbooks environment.

[Windstorm]

I personally like mongoose's ultimate equipment series. Lots of stuff in there for low level and martial characters, and most of leans to the underpowered side. They're also pretty much entirely mundane equipment, so good for low magic settings.

There are two gotchas, and that's the turtle suit armor and the psi steel material, and they're nothing some minor adjustments can't fix.

Book list:
Ultimate equipment guide 1&2, more ultimate equipment; all by mongoose publishing.

[cosmonuts]

Thanks for the reccomendations.

I vaguely recall a Japanese mythology sourcebook which sounded interesting and was praised for being accurate to the actual mythology. I don't remember its name. Anyone know what I'm talking about?

[Seerow]

I'm a fan of DSP, both their 3.5 and PF stuff (though I think the PF stuff has mostly supplanted the 3.5 books).

[Gnoman]

I personally like mongoose's ultimate equipment series. Lots of stuff in there for low level and martial characters, and most of leans to the underpowered side. They're also pretty much entirely mundane equipment, so good for low magic settings.

There are two gotchas, and that's the turtle suit armor and the psi steel material, and they're nothing some minor adjustments can't fix.

Book list:
Ultimate equipment guide 1&2, more ultimate equipment; all by mongoose publishing.

From the same publisher, the Encyclopedia Arcane series is fantastic. 23 volumes (only 22 of which are good, as Nymphology is a shoddy BoEF knockoff) that each provides a completely new system of magic, not merely new spells (for example, Demonology includes rules for selling your soul to devils, selling someone else's soul, breaking demons to your will and enslaving them, getting possessed by a demon that you failed to break and enslave, while Crossbreeding includes rules for fusing creatures together (think Owlbears)). Balance is a bit off in places, particularly with the two monster making books (which unfortunately lack a built-in way to determine CR of the products), but these are fairly easy to work around.

[Sartharina]

I hear good things about Hyperconscious

[Windstorm]

Thanks for the reccomendations.

I vaguely recall a Japanese mythology sourcebook which sounded interesting and was praised for being accurate to the actual mythology. I don't remember its name. Anyone know what I'm talking about?

That's the Kitsunemori campaign setting, which is available for sale online Here (http://www.rpgnow.com/product/20740/Kitsunemori-Campaign-Setting?it=1). its a fantastic book, and a lot of really great attention to detail. the reason I don't put it on a "you should include this" list is because like any campaign setting supplement, unless you have a way to work it into your setting allowing elements from it can prove problematic. However if you can deal with that issue I don't see any reason not to include it.

for the oriental theme there is also D20 Rokugan, which I have no experience with but hear good things about.

[Rubik]

I hear good things about HyperconsciousHyperconscious is amazing (barring a couple of things -- namely, Detonate Psicrystal [which nobody should ever, ever use] and the Stabilize Construct power, which needs major errata before it's even vaguely usable). Some of the low-level powers are very much underwhelming, but otherwise, it's a great book in a lot of ways.

Untapped Potential, by Dreamscarred Press, is also pretty great. It's partially predicated on your use of Hyperconscious, but it's not necessary to have both to use it.

[BWR]

Are you interested in mere mechanics or some fluff as well?

As mentioned, the Encyclopedia Arcane/Divine series was on the whole pretty good. Some of them are better than others (I found Necromancy to be a bit of letdown, for instance, especially compared to 2e's Complete Book of Necromancers), but they are definitely worth a look if you want something based on existing casters but with a fresher PoV. Chaos Magic was my personal favorite. The power level varies, from the useless to the brokenly good. It's been a while since I've read them, but I can't recall anything quite as abusable as e.g. Gate off-hand, but I'm pretty sure there are some silly things there.

d20 Rokugan and the entire series of AEG's dual-stat books is great if you want an introduction to the Legend of the Five Rings setting. Lots of R&K purists are strongly - dare I say rabidly? - opposed to the d20 version and anything resembling D&D, but it's a pretty decent job on the whole. Combat types get a lot of love, but I can't really think of anything that is as powerful as WotC stuff. If you want an introduction to the setting, you're better off finding a copy of the 4th edition of the R&K RPG rather than trying to dig up copies of the d20 stuff. If you like the shugenja class, there is a lot of love for it in Magic of Rokugan and Way of the Shugenja.

Apart from those, I generally liked Malhavoc's stuff, like Anger of Angels, Chaositech (Chaos-tainted magitech that can give you powers and twist you), When the Sky Falls (magical comets/meteors hitting the planet), Requiem for a God (what to do if your god dies), and more. Hyperconscious had a lot of fun stuff, but I used it more for the monsters than the powers or classes (I liked the malafides, illithid rip-offs though they were). Some of the powers are just plain ridiculous and shouldn't be allowed in a game. Most are ok.

[Prime32]

Just about anything by Dreamscarred Press (http://dsp-d20-srd.wikidot.com/) is equal-to-better than WotC writing, to the point where I've seen DMs put blanket bans on third party then allow their stuff because "they don't count".

Kitsunemori is a great setting book, though it has some completely broken mechanics.