Yea, filesharing is fairly common on college campuses. BitTorrent and DirectConnect are some of the larger ones I've heard of - but I'm sure there are others. The main problem is staying off the RIAA/MPAA watch list - don't use any programs they're taking an interest in, just out of paranoia
One of the more interesting file sharing concepts I've seen recently was MUTE - an anonymous P2P network. I'll try to dig up the link.