Social Engineering
- Discussion forum about the insecurity of humans known as social engineering.
- http://www.socialengineering101.com

Spywire Forums
- Forum dedicated to bringing knowledge to people starting out in hacking.
- http://spywire.net/forum/index.php

SecureRoot
- One of the worlds longest established hacking forums, offering resources covering everything from cracking to phreaking.
- http://www.secureroot.com

The Forbidden Web Archive
- Security and Development Forum with a Security Basics Forum and Vuln-Dev.
- http://www.forbiddenweb.org/

HFX International Forum
- Discussion forum for topics surrounding the underground, technology and the like.
- http://forum.hfactorx.org/