Go and play there.
Subscribe in this group and you will get the latest security related incidents, Security related books, white papers,etc.
Some useful codings (in Unix and Linux Security), research papers ,etc.
This is a site which couldn't be easily found in search. You can find a lot of information related to cryptography, E-mail security, etc.
Best site to learn about Linux Security.
Lots of Information related to Penetration testing, latest Vulneribility reports, etc.
Good readings in all the fields of security ( like IDS , Cryptography, Firewalls, etc).
Open Source penetration testing tools like tools like nmap, various exploit code , etc.
Steven M. Bellovin's research papers.