I recently found Freecycle, thanks to Clinton Hammond, and joined the nearest group, which has over 100 memebers. (This is UK btw). I'm just arranging to collect a bookcase...the first thing I've actually got from it. Haven't given anytihgn away yet, but I expect it won't be long.
My brother has told me about the American thing of leaving things on the curb with a sign on saying "Free". He got a good office chair that way. We couldn't do it where I live 'cos it would block the footpath...we don't have a grass verge or anything.