Missing Open Source Security Tools?

Kinetic writes "There are many great open source security tools out there, Nmap, Nessus, and DSniff, just to name a few. However, with the world of security constantly changing, this begs the question, what open source security tools are missing? What commercial security tools have no viable open source alternatives? When securing/testing/exploring networks (home or enterprise), what security tools/applications/functionality are lacking (or non-existent) in the open source world?"