The Samurai Web Testing Framework is a live linux environment that has been pre-configured to function as a web pen-testing environment. The CD contains the best of the open source and free tools that focus on testing and attacking websites. Samurai includes many other tools featured in this list, such as WebScarab, ratproxy, w3af, Burp Suite, and BeEF.
For downloads and more information,
visit the Samurai Web Testing Framework homepage.