http://www.incidents.org/
-- updates with graphical reports of incidents across the world!

http://www1.dshield.org/ipinfo.php?ip=?
-- A searchable database for IP information.

http://www.cert.org
-- contains all the latest information on what's happening in the security with computers.

http://project.honeynet.org
-- one of my personal favorites! Honeynet.org project exams security scans and holes in other linux boxes.

http://home.eunet.no/~pnordahl/ntpasswd
-- nt password utility and registry editor. Allows you to change almost NT based systems password and edit the registry.

http://spamcon.org/directories/shared-blacklists.shtml
-- This website provides you with information on e-mail blacklists.