But because I'm such a nice guy, here's a link for you.
http://forums.gleemax.com/showthread.php?t=952766
[...] So I was wondering if you guys could help me build the best damn bard ever. [...] You can use most books, and stuff from Iron Kingdoms is encouraged.
"Wow, that's mighty nice of you that we can use most books. No, really, I do appreciate that! Now why don't you go use some books yourself?"
...is probably the answer many people here will find fitting for such a request as yours. While you may get a few snippets of advice such as "Go Sublime Chord!" or "take Song of the Heart!", your plea does not accord to the posting guidelines.
First, it is considered rude to just ask for "the best damn bard ever". This isn't customer service. You could, you know, put in a little work of your own. Like reading a handbook, for example. Or finding out about one of the more powerful bard class features. Browse your books, browse the forums, gather ideas, develop an understanding of what's possible and what's not.
Also, you could be a little more specific. What kind of Bard? Most or all Bards will be "a decent support charachter". Any ideas about class features you like or find interesting, combat capability, prestige classes whose flavor you like, spells you find exciting, feats...?
Basically, give us something to work with, do your homework, come up with a basic build or build stub, ask specific questions: Not "build me a bard!" but "Do you think Extra Music coupled with Lyric Spell is worth the investment of feats?". Not "I wanna be support and make for good leadership!" but "Is it more useful to a support character to go the Exalted route (Song of the Heart, Words of Creation) or the sinister route (Mindbender PrC, Mindsight, Doomspeak)?".
I think you'll catch my drift. Also, I hope you'll find some of the hints useful.
EDIT: Ninja'ed and double-Ninja'ed!
I would also like to see a 'straight' bard 20 build optimised.
There are about five in the single class build thread found in the link of the second post...
So adding on top of that I would take a human bard, and possibly (if you DM allows it) with the draconic template. Nice +2 to STR,CON and CHA, with a +1 natural armor and the equivalent of dragonblood subtype (well actually better than the feat of the same name). You want human so you can multiclass. Check with your DM if you're allowed to buy the LA following the UA guidelines.
Second take a hit onto your bard level by taking one level of dragon shaman. Not the greatest thing some will say but you'll have the opportunity to take 3 auras which you can use all the time, with the very usefull vigor aura granting a limited form of fast healing; this will alleviate the cleric's burden a lot in the healing departement between fight, bringing everyone half-way to their full hp; now talk about supporting. (ok I know there's a reserve feat that does something similar but in case you can't take the reserve feats). Also take sense and resistance as they are the only 2 other useful auras with a +1 bonus (damage might be useful if you let it count for ability damage, which not every DM agrees to).
Then remember to boost you aura of courage as much as you can.
Remember that you're a spellcaster. You have acces to healing spells (choose a few to complement your vigor aura), and a few offensive sonic spells, to which few creature are immuned. On top of your other abilities, this can make you dangerous in a fight. You could spend a feat on Extra Spell which allow you to select a spell from any arcane spellcasting list (or so I beleive; in essence, this work like the feat expanded knowledge for Psionic characters).
Also remember that you're a spotaneous spellcaster, and this gives you access to a few unique feat, like versatile spellcaster (RotD).
That's all I would personnaly add to the great builts you can find in Empowell13's link.