Ran across this link today: https://makelovenotspam.com/intl/index.html.
It’s a screensaver that targets known spammers, slowly eating up their bandwidth. The visual is a map of the world with almost missle-command-like arcs showing weapons of spam destruction raining down on the evildoers. Each target site also has a little bar graph showing how much bandwidth they have left.
The screensaver will only use 3.4 megs of your own bandwidth in a 24 hour period. But the cumulative effect should do some damage if enough people use it. Not sure how effective it is, but it’s kind of satisfying to watch.
Available for Mac and PC.