Tor

The Tor Project
www.torproject.org
Free

Tor (short for The Onion Router) is a combination of client software and a network of encrypted proxies and data routers that effectively defends against most kinds of network surveillance. By using it, you make it very hard for a third party to determine what Web sites you�re visiting and even who you are and where you�re located.

Most Internet communications are easily traceable: Each packet has the IP address of its source (you) and its destination (a Web site) in its header. However, the Tor client encrypts your packets and routes them to a random Tor node, which then routes them to another random Tor node, which then decrypts them and passes them on to their destination. Return communications follow a similarly random path. Yes, the system can be slow, as it relies on the bandwidth of volunteers for the nodes, but its popularity increases your anonymity further: Who can sort through all those packets to find just you?

Source of Information :  CPU Computer Power User November 2010