Hacker lab engaged in vulnerabilities research. Security papers, full disclosure advisories and current projects. Also features a FAQ on hacking techniques. http://www.nmrc.org/
Organization dedicated to the research and demonstration of vulnerabilities in network services and communication security. Offers papers, security tools, exploit code, advisories and a discussion forum. http://www.xfocus.org/
Team of security researchers. Features news, original papers and advisories, presentations they have given, and tools they have written. http://razor.bindview.com/
Offers details regarding select viruses, overflow and security exploits, bios tools, and crytography. Also features book reviews on assembly programming and computer security. http://www.11a.nu/