Razor
- Team of security researchers. Features news, original papers and advisories, presentations they have given, and tools they have written.
- http://www.bindview.com/Services/Razor/

Xfocus
- 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/

Nomad Mobile Research Centre
- 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/

enZo
- Coding group. Offer hacking tools and vulnerability exploits.
- http://www.enzotech.net/

HATE (Hackers Against Tyranny Everywhere)
- Anarchy, HAcking, Phreaking files for newbies.
- http://hnsg.net/

TwistedinterneT ServiceS International Inc.
- Underground Hacker site with an extensive archive and library.
- http://www.twistedinternet.com/

Crewl Underground Madness
- Belgian group specialized in computer and network (in)security, hacking, coding and phreaking.
- http://www.blackhat.be/

Attrition.org
- Attrition is an eclectic collection of internet and computer security resources.
- http://www.attrition.org/

Digital Information Society
- Exploit archive, phreaking information, and group member pages.
- http://www.phreak.org/

Moloch Industries
- A New York hacker group.
- http://www.moloch.org/

HackHull
- Group of hackers in the United Kingdom. Information about meetings, projects, and links to personal pages.
- http://www.hackhull.com/

Progenic Security
- Security advice and exploits.
- http://www.progenic.com/

Twentythreedotorg
- SoCal's hacking group. Canadian free since 1999.
- http://www.23.org/

Cult of the Dead Cow
- Offers blog, team background, tools and BackOrifice downloads, and news archive.
- http://www.cultdeadcow.com/

Eleventh Alliance
- 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/