Security Focus
SecurityFocus is designed to facilitate discussion on computer security related topics, create computer security awareness, and to provide the Internet's largest and most comprehensive database of computer security knowledge and resources to the public. It also hosts the BUGTRAQ mailing list.
http://www.securityfocus.com

ESTec Security
ESTec Systems Corp. offers information security consulting, policy and procedure development, certified audit assistance, ISO 27001, ISO 17799, BS 7799 implementation services.
http://www.security.estec.com/

Security Intelligence Services
Offers security management consulting, security analysis, and security education. Based in Haledon, New Jersey.
http://www.securitypersonified.com

International Security Defence Systems
specialists in high risk aviation security services and training, airport security and sky marshal training and consulting, ICAO, DfT and TSA standards applications, behavior pattern recognition training
http://www.isds.info/

SSS Lab.,Inc.
Windows Security Officer is an autonomous provider of log-on and resource restriction security application integrated with, yet independent of, the Windows operating system. It has the capability of providing extremely strong, secure control of who can access a personal computer resources, and exactly what they can do and when they can do it while they have access to those resources.
http://www.mybestsoft.com/index.html

Cambridge Univ's Computer Security Group
Research Interests: Security Protocols, Formal Methods, Reliability of Security Systems, Medical Information Security, Cryptographic Algorithms, Steganography and Information Hiding, Digital Watermarking, Hardware Security, Electronic Commerce
http://www.cl.cam.ac.uk/research/security/

Southwest Security and Investigations
A security agency dealing with site security, industrial security and counter espionage.
http://www.go-ssi.com

Security for .NET
Implement managed role-based security for .NET Framework. The Security for .NET enables you to manage Windows security.
http://www.blackbytes-components.com/product.aspx?id=1&mt=1

Help Net Security
Help Net Security is a daily updated security related site. We offer information on the latest advisories, viruses, press releases, papers, etc. The site also has a large download section that helps you get protected, a well-stocked bookstore, and the largest Security Database of security products.
http://www.net-security.org

IT Security Cookbook
Comprehensive online book including: Computer/Network security, Internet, Risk analysis, UNIX, NT, Encryption, ITSEC
http://www.boran.com/security/