RetroShare is pretty cool. Initial release was in 2006. > Retroshare is a free and open-source peer-to-peer communication and file sharing app based on a frien

RetroShare is pretty cool. Initial release was in 2006. > Retroshare is a free and open-source peer-to-peer communication and file sharing app based on a friend-to-friend network built on GNU Privacy Guard. Optionally, peers may communicate certificates and IP addresses to and from their friends. > RetroShare is a decentralized, private, secure, cross-platform, communication toolkit. RetroShare provides file sharing, chat, messages, forums, channels and more.