Freenet is a large-scale peer-to-peer network which pools the power of member computers around the world to create a massive virtual information store open to anyone to freely publish or view information of all kinds. Freenet is: Highly survivable: All internal processes are completely anonymized and decentralized across the global network, making it virtually impossible for an attacker to destroy information or take control of the system. Private: Freenet makes it extremely difficult for anyone to spy on the information that you are viewing, publishing, or storing. Secure: Information stored in Freenet is protected by strong cryptography against malicious tampering or counterfeiting. Efficient: Freenet dynamically replicates and relocates information in response to demand to provide efficient service and minimal bandwidth usage regardless of load.
More info:
hxxp://freenetproject.org/cgi-bin/twiki/view/Main/WebHome