some useful links

www.google.com best search engine and you can find any thing with the proper syntax

darknet.org.uk Darknet - The Darkside. Ethical Hacking, Penetration Testing & Computer Security.

www.metasploit.com  Open-source platform for developing, testing, and using exploit code. Downloads and release notes. [Windows, Unix]

milw0rm.com/ exploits and 0day exploits database.

packetstormsecurity.org Information and computer security full disclosure web site