This is a small community. For product, I think it's pretty hard to dispute that BitMit is the biggest right now. If you know of one bigger, please share.

EDIT: Oh, yes, SilkRoad is probably bigger. But at the moment it's underground. I hate to qualify my statement, but I will anyhow. BitMit is the biggest, closest-thing-to-a-white-market that BitCoin has.