Ethical Hacker Community Forums

Some say that Nmap is an old tool, and this is true. It nonetheless is still useful, because the authors tend to keep up with the times.

http://www.insecure.org/nmap/

Insecure.org also has a list of the Top 75 Security Tools. No telling how old the list is, but it is a good starting point.

http://www.insecure.org/tools.html

Don