“Freenet is a censorship-resistant distributed data store.” [src]
“I2P is an anonymous peer-to-peer distributed communication layer designed to run any traditional internet service (e.g. Usenet, E-mail, IRC, file sharing, Web hosting and HTTP, Telnet), as well as more traditional distributed applications (e.g. a distributed data store, a web proxy network using Squid, or DNS).” [src]
Tor is a data routing software which provides anonymous access to regular websites and -services. There is also support for Freenet-like functionality.