You want to learn about serious SPAM? Read the Net-Abuse FAQ by Scott Southwick and J.D. Falk. A most excellent piece of work.
One of the best all 'round resources for spam fighting is Spam Killer Central.
How to Trace Spams, an article on the interpretation of header information, and links to InterNIC Whois and DNS Lookup. This site has lots of resources collected.
Don't miss the news.admin.net-abuse.* FAQs and other documents.
And for anti-spam with attitude, see S.P.U.T.U.M.'s Anti-Spam Tactical operations HQ.
times since May 25, 1998.