We still don't know who Dragon is, even in the manga he hasn't been mentioned since, just to keep your hopes down...

Jenbei - is the merman schibukai, apparently Arlong was under him before, but no picture of what he looks like, or that I know of.
Hawkeye Mihawk - Best swordsman in the world
Doflamingo (This guy is cool) - Looks like he got some psychic powers
Bartholemew Kuma - Big strong guy. Dunno what he does.

3 More unknown...

We don't know if White Beard or Shanks are Schibukai though. The anime or manga never states so. But I think their at war. [img]i/expressions/face-icon-small-smile.gif[/img]

Black Beard is applying for a Schibukai spot to replace Crocodile. So maybe 2 more unknown, if he does get the spot.