I've had a pretty good time playing around at Quora lately. It's a website where people ask and answer all kinds of questions framed in various "categories." Once you figure out how to separate the interesting questions from the usual "rankings" kinds of questions, it's pretty fun to see just how thoughtful the participants are both in framing questions and in providing answers. And there are lots of participants from all over the world.
Be careful, though. I imagine it's pretty easy to become addicted to the site.