I have been a fan of http://www.Experts-exchange.com for a long time now. I registered in Sept 2003 and have earned 23,285 points. It is fulfilling to help people. I love that. And the whole structure is set up to easily ask questions and easily answer them. Recently (last year) they did a redesign which I think makes it one of the best user experiences on the web. It’s clear and elegant. The visual design is strong. Great use of chunking and contrast.
Overall, I think it is one of the best sites on the web. It would be cool if they added a jQuery section.
Great work and kudos to the Experts-Exchange design team.