GridChat is a highly expandable peer-to-peer network that has no central server.
NEshare is a Peer-to-Peer toolkit.
cryptic6 is an encrypted P2P program based on the principle of 6 degrees of separation.
phpjb is a php interface / management system to your audio files and feeds.
Adagio is a Gnutella2 server which aims to provide a very configurable, highly reliable cross-platform daemon.