I'm young, and I've been doing a bit of traveling over the last couple of years (China, Vietnam, Ireland, Califorinia and the Eastern Seaboard), and I've heard of couchsurfing from more than a couple of people that I've met, but I've yet to try it. I like the idea that people you meet online are real and hospitable, but personally, I wouldn't want to do that. I like hostels because you get to meet many young traveler types that have varying experiences and cultures, and meeting together for a meal or a soccer match with that many people from that many backgrounds is probably one of the greatest things ever. I think that maybe it would be hard to meet as many people (save pubs I suppose) if you were couchsurfing.