Freeware system optimisation and privacy tool that erases Internet history and other unused files, and cleans up orphaned registry entries. [Windows]

A product of the US Navy Research Lab, the Onion Routing is an Internet based system to prevent eavesdropping and traffic analysis attacks. It is now "off-line" but listed in the ODP for completeness and potential new developments.

Provides a free anonymous web surfing service and a list of resources for anonymous use on the Internet. Registration required. Also offers anonymous webhosting.

Free service to show web surfers how much information their browser can reveal about their system when visiting normal web pages.

Hides short messages in a fake spam; the recipient can decode them after receiving the real-looking "unsolicited commercial e-mail".

Prevents a site from appearing in the server logs of referred pages as a referrer.