Anti-spammers are like gazelles. They're graceful, charming, and beautiful. Spammers, however, are like gazelle gut worms—they're gross, cause horrible diarrhea, and eventually kill the host. A perfect example of this is Blue Frog. Blue Frog, and their service Blue Security, originally offered folks a way to spam spammers. First, customers would send spam to the Blue Frog service which would reply to the spammer with a request to remove the victim from their list. If that didn't work, the system would fill out any webforms it found on the spammer's website with requests to remove the victim. It seemed to work fairly well.

Unfortunately, the spammers DDOSed Blue Security until it died. Because spammers are shit-eating scum, they had hundreds of zombie machines at their fingertips and slammed Blue Frog into paste. Oh well. Couldn't someone work out a SETI@Home sort of thing that does this exact same thing? Torrent the download and make sure there is no one point of attack?

Web attacks end anti-spam effort [BBC]
Blue Frog killed by Russian spammer [TheInquirer]