The bard is a hybrid class; it started off as a fighter/thief/druid hybrid, and in 3e it's a skilled arcane class with some divine spells. So I'd say the bard could use a boost in all three areas (combat, skills, and spells) to make it more than just a beguiler with music or a rogue with spellcasting.

For combat, we can fall back on the songs, since we all know an Inspire Courage-specced Snowflake Wardance bard can be a pretty good combat monster already. Let the bard pick from among all the published songs (skald, dirgesinger, virtuoso, seeker of the song, heartfire fanner, etc.), fold in some common useful metamusics like Lingering Song to the basic music mechanics, and bump up the base numbers so the bard can be a superb buffer out of the box (while removing things like Song of Creation and badges of valor so he can't go from superb to broken).

For skills, Bardic Knack and Bardic Lore are already pretty darn good; a small change, adding bonuses for certain skills on top of the effective ranks for all skills, can make them even better. Normally just throwing numbers at a class won't raise its tier, but giving the bard +Yes to skill checks opens up things like walking through force walls, running on air, swaying armies with his words, and other gamechangers.

For spells, since it's an arcane/divine hybrid already, here's a radical idea: let the bard learn spells from any spell list. Same spells known and per day, but now it can pick from the best spells out there. Unlimited access to all spells can be broken even if limited to 6th level spells, however, so let's group them into colleges, 1e style (though obviously specific names like Fochlucan or Mac Fuirmidh, aren't necessary). Maybe one for each traditional type of bard: trickster, sage, face, sonic blaster, buffer, bladesinger, and nature guy, sort of like specialist wizards but based on bard theme rather than spell theme. A given bard could pick spells from the bard list plus spells from any other list in X colleges of his choice.

So this bard can do a bunch of things in combat (summon critters and buff them with +6 inspire courage, blow people away with lightning and thunder, etc.), in exploration scenes (run up cliffs and over gaps, tell you the exact weather patterns of this particular mountain, etc.), in downtime (craft amazingly, raise armies, etc.), and more. It doesn't have the sheer world-shaking power of most Tier 1s without higher-level spells, but I think the sheer versatility of multiple spell lists plus epic skills plus songs makes up for it, and you can easily scale the power up or down to taste based on the exact music bonuses, the number and breadth of colleges, etc.