I would love to learn a little bit about security. One common thing that not enough people do is suppress the errors of mysql functions. The errors should be suppressed and custom error messages should be created, otherwise mysql may spew out info that hackers can use to their advantage...
A security forum would be a good idea, but I think that most security-related questions could be asked in the Newbies, General Help, or Coding forums...I would love to see this forum, but realistically, I don't think it'll happen....