Does Blurtit Count? Lol! I love how user friendly this site is, that is actually has a "How to" video and that if you want to you can actually just chat with people, it's not solely to ask and answer questions. That layout is also great.
The few bugs there are (notification bar :P) are still minor things.
Simplicity is what really draws me to a site. It mustn't be overly complicated.
Blurtit's a winner for me :)))