SpamCop.net - http://www.spamcop.net Spam reporting tool. Users can report spams, and then SpamCop sends email reports to ISP's and spamvertized websites.
The Spamhaus Project - http://www.spamhaus.org Anti spam info and DNS black list.
Rick's Spam Digest - http://www.rickconner.net/spamweb/ A good site with a lot of detailed info about spam.
- http://www.spamcop.net