I did start getting e-mails soliciting kiddie porn. I forwarded those to the FBI....
SpamCop's cool because it automatically parses the header to extract all the return-path hops, and finds the real IP addresses. (One trick everyone seems to use is they put completely bogus From: addresses in the header.) The report it generates shows the spam originated from some account in .mx, .cn, .kr, .es, .se ... then it got routed thru some ISP's open relays in another country, etc. So SpamCop sends the report to every ISP it could detect along the path, as well as the ISP for any websites mentioned in the email body, etc. etc. Who knows where the spam REALLY originates???
Anyway, it's the best solution I've found so far that doesn't take up all day doing the legwork myself. :-)