I'm not picky. Preferably something low to mid levels (I'd rather work a character up than have him decked out right out of the box), mostly core/FR. I'm a big horror fan, so I'd be all over something in that genre as well. I actually wouldn't mind playing some d20 Modern as well; I've got the sourcebook around here somewhere that's dying to have the dust blown off of it.
That being said, if someone wanted to throw an 18th level Eberron campaign at me instead, I'd probably be up for it as well.