ISO 27001 Security Forum - is where the ISO 27001 implementers share about their experiences, compile documents and made available for forum members. Actually, everything that you might want to know about ISO27000 family can be answered in this forum. Strongly suggested that you check this out and join, it is free but you need to be approved to get passed.
Bugtraq - hosted by Security Focus where fresh information about systems security vulnerabilities and detailed discussions and announcement are posted, moderated list.
Firewall Wizards - hosted by ICSA Labs, an independent division of Verizon Business, provide in all angle about firewall and security related information. Accordingly, it sets standards for information security products and certifies over 95% of the installed base of anti-virus, firewall, IPSec VPN, cryptography, SSL VPN, network IPS, anti-spyware and PC firewall products commonly deployed in the world today.
Penetration Testing - is all about professional penetration testing and general network auditing.