W.A.S.T.E. (Score 5, Informative)

I've used WASTE for a long time. It has in interesting history....involving AOL and others. WASTE is a VERY secure private p2p network. It uses keys similar to pgp keys and can use over 4000+ bit encryption if needed. However, the network does seem to fall apart after about 50 or so people have joined. It is only good for small groups, imo. If you have a MAC, i wouldn't even bother was WASTE for now, it's current development stage give basically no functionality. For pc users who just want to trade files with their friends, etc, its a great alternative to other p2p.