Freenet

The Free Network Project (Freenet)
Free software which lets users publish and obtain information on the Internet without fear of censorship. To achieve this freedom, the network is entirely decentralized and publishers and consumers of information are anonymous.
http://www.freenetproject.org/

FreeWeb
A user-friendly GUI-based Freenet client for site insertion.
http://freeweb.sourceforge.net/

Frost
Java-based file sharing and messaging client for Freenet.
http://jtcfrost.sourceforge.net/