I like Stack Overflow, Jeff Atwood's programming Q&A site. It's quickly become a go-to place for all kinds of programming questions. It's certainly easier to find a definitive answer there than trying to wade through a thread in a mailing list archive. The social dynamics seem to be working and a definite community has evolved.

I've been going there more often recently. I browse the hot questions and I often learn something from them.

I'm answering some questions too. I've been doing this for twenty years on Usenet and mailing lists. I might as well get a little credit for it on SO. My reputation is 131 as I write this: I expect it will grow.