I, Mongoose

I found out about these recently on the Ethical Hacker forums. They are live CD's containing operating system installs with deliberate flaws built into them for people to discover and exploit to gain access to the system. They are intended as practice labs for pentesting and I reckon that they're a brilliant idea. I've just about got the first one sussed and it's been a very interesting learning experience, exposing me to a range of security tools which I've never had a reason to use before.

Anyone with an interest in information security or penetration testing should definitely give these some attention.