Security Reference
Caida Presentations
http://www.caida.org/outreach/presentations/

CERT Coordination Center
http://www.cert.org/nav/index_green.html
http://www.cert.org/octave/
http://www.cert.org/csirts/

Center for Internet Security Benchmarking tools
http://www.cisecurity.org/

Cisco's Safe Documentation
http://www.cisco.com/en/US/netsol/.../networking_solutions_package.html

Team Cymru Document List
http://www.cymru.com/Documents/index.html

Federal Agency Security Practices
http://csrc.nist.gov/fasp/

First
http://www.first.org/resources/guides

JANET
A Suggested Charter for System and Network Administrators

NSA Guides
http://www.nsa.gov/snac/

OWASP Guide to Building Secure Web Applications
http://www.owasp.org/documentation/guide/guide_downloads.html

Oreilly's Onlamp
http://www.onlamp.com/security/

Internet Security Alliance Common Sense Guides
http://www.isalliance.org

Microsoft Security Guidance Center
http://www.microsoft.com/security/guidance
Same site in Brazilian/Portuguese, French, German, Italian, Japanese, Korean,
Simplified Chinese, Spanish and Traditional Chinese
http://www.microsoft.com/security/guidance/worldwide
Microsoft TechNet Security Guidance
http://www.microsoft.com/technet/security/guidance/default.mspx

Nanog's Security Curriculum
http://www.nanog.org/ispsecurity.html

RFC 2350 - Expectations for Computer Security Incident Response
http://www.faqs.org/rfcs/rfc2350.html
RFC 2196 - Site Security Handbook
http://www.faqs.org/rfcs/rfc2196.html
RFC 2827 - Network Ingress Filtering
http://www.faqs.org/rfcs/rfc2827.html 
RFC 2504 - Users' Security Handbook
http://www.faqs.org/rfcs/rfc2504.html

SANS Reading Room
http://www.sans.org/rr/ 

Sun blueprints
http://www.sun.com/blueprints/browsesubject.html

Sun System Administration Best practice
http://www.sun.com/bigadmin/features/articles/bestpractices.html

Acknowledgement

This is a collaborative effort from the FIRST community - moderated by Gavin Reid. Thanks for all the great suggestion and feedback.