Exploits

Exploiting Caller ID - The Software Orange Box is a free proof-of-concept tool which can spoof most forms of North American Caller ID.
http://www.artofhacking.com/orange.htm

Hack A Day - A hardware hack every day.
http://www.hackaday.com/

Ethical Hacking Course - Commercial hacker training course on how to write and use exploits.
http://www.infosecinstitute.com/courses/ethical_hacking_training.html

Security Focus - Provides security information to all members of the security community, from end users, security hobbyists and network administrators to security consultants, IT Managers, CIOs and CSOs.
http://www.securityfocus.com

Ill Mob - Home of a number of 0-day exploit authors. Many creative Trojan droppers and methods are released here.
http://www.illmob.org/

PacketStorm Security - Packet Storm is a non-profit organization comprising computer security professionals that are dedicated to providing the information necessary to secure the networks world-wide. It publishes new security information on a global network of websites. The organization offers an abundant resource of up-to-date and historical security tools, exploits, and advisories. It provides network security professionals, researchers, and all other interested individuals with the ability to analyze and learn from the tools, processes and mindsets of their opponents, as well as offering the tools needed to build and test defenses against them.
http://www.packetstormsecurity.org/

Fyodor's Exploit World - A large and descriptive exploit archive organized by affected operating systems.
http://insecure.org/sploits.html

Metasploit Project - The Metasploit Project is an open source computer security project which provides information about security vulnerabilities and aids in penetration testing and IDS signature development. Its most well-known sub-project is the Metasploit Framework, a tool for developing and executing exploit code against a remote target machine. Other important sub-projects include the Opcode Database, shellcode archive, and security research.
http://metasploit.org

SecWatch - A site dedicated to the latest in security - all the latest and archived exploits and vulnerabilities.
http://secwatch.org/

milw0rm.com - Exploit database separated by exploit type (local, remote, DoS, etc.)
http://www.milw0rm.com

FrSIRT Exploits Archive - Archive of current 0day exploits from European and Asian sources. French and English language content provided.
http://www.frsirt.com/exploits/

Security-Protocols Exploit News - A up to date security and exploit portal, provides commentary on many popular exploits as they develop in the wild.
http://www.security-protocols.com

Phenoelit - Custom built network tools designed to take advantage of the exploits within many network hardware systems. Also the home of the k0ld LDAP brute force utility. A must have for many professional penetration testers.
http://phenoelit.de/fr/tools.html

Canvas Exploit Platform - A commercial exploit platform similar to metasploit. Has built in memory resident shells that are cleared when the machine is rebooted. Perfect for cleaning up after a penetration test.
http://www.immunitysec.com/index.shtml

PullThePlug WarGames - Place for Programmers and Hackers to hone their technical skills by completing challenging wargames and Programming Challenges. Including Network Programming, Defeating PaX, Buffer/Heap Overflows, Format Strings etc.
http://www.pulltheplug.org/

Security Tracker - Archive of exploits and security advisories
http://www.securitytracker.com

0-Day Exploits and Tutorials - DataStroghold.com Unveils how exploits and other hacking techniques are performed, in a clear and concise method. Frequently updated and always interesting.
http://www.datastronghold.com

malware.com - A group that develops as well as discloses software exploits on many of the security mailing lists. Mainly specializing with Microsoft Office and Internet Explorer Vulnerabilitys.
http://www.malware.com/