[Jimbo]

Depends on what your are making, but some fun and powerful characters:

Long-range specialist:
Elf
Rogue
Wizard
Spec long bow
point-blank
rapid fire
combat casting
and other goodies
no armor (buck-nakked!)
with a dire badger to boot. Going with 7 rogue/13 wizard for the character I'm playing right now.

Sneak Attack Jack! :
Human
11 rogue
9 fighter
Lots of str and dex.
Two routes to go here (well three sort of), go with big 2handed weapons for some massive damage, or duel-weld, or use an exotic double weapon. Each has +'s and -'s depending on what other feats you want.

Improved bounty hunter:
7 rogue
13 fighter
decent str,con, and intel.
This is a very well rounded character that can cast spells from scrolls, pick locks, set traps, and disarm them. It is fun if you have to explore every corner and like to set up your fight like a game of chess (plan out the traps, what type, and how or what to use extra for the fight from potions to scrolls).

For the Official Campaign that came with the game I'm likeing my rogue/wiz elf since all quests are open to me and I'm not worrying about traps or locks.