I2P, the Invisible Internet Project, is meant to provide a free anonymity layer, so users can communicate anonymously using a range of applications.
Protect your communications from dragnet surveillance and monitoring by third parties.
I2P is an anonymous network, exposing a simple layer that applications can use to anonymously and securely send messages to each other. The network itself is strictly message-based (a la IP), but there is a library available to allow reliable streaming communication on top of it (a la TCP). All communication is end-to-end encrypted (in total, there are four layers of encryption used when sending a message), and even the endpoints ("destinations") are cryptographic identifiers (essentially a pair of public keys).
I2P Provides You With The Following Options:
Email: Integrated webmail interface, a plugin for serverless email.
Web browsing: Anonymous websites, gateways to and from the public Internet.
Blogging and forums: Blogging and Syndie plugins.
Website hosting: Integrated anonymous web server.
Real-time chat: Instant messaging and IRC clients.
File sharing: ED2K and Gnutella clients, integrated BitTorrent client.