Security Links

Insecure.org - Creator of Nmap
Sectools.org - List of Top 100 commercial and free

Partners

Qualys - Security Vulnerability Scanning
NTObjectives - Application Penetration Testing

Security Tools

Security Focus - Great site for information and learning
Dshield - Internet Storm Center - Bad IP lookup
OWASP - Open Web Application Secuirty Project
KeePass - Encrypted Password Database
Osiris - File Integrity for Free!
Log Analysis.org - Log Analysis Tools

Audit Related Links

PCI Security Standards Council
Visa CISP

Encryption (Requirement 3.4)

TrueCrypt - File based encryption
GNU Privacy Guard (GPG) - File Encryption