Ok, this is an interesting one: Ol' Lycos has apparently developed a screen-saver based system that will launch DDoS attacks against websites known to spam: http://news.bbc.co.uk/2/hi/technology/4051553.stm The system, as the article describes it, is actually more of a targeted Slashdot effect than a DDoS. Each screen saver checks in with the Lycos server to find out which site (apparently hand-picked to eliminate collateral damage) to pick on, then starts sending HTTP requests to the site periodically. Their system monitors the performance of the sites to make sure they specifically DON'T go down, merely run slow as a result of massive traffic. The theory is that the bandwidth costs will make it economically unviable to spam people--if you make less per month than your site costs to run, there's no point in it. They've also worked at making the useage low so as not to bog down the net, only requesting 4MB of data per day per user. I'm not so sure it's an ethical idea, and I'm also not so sure it'll work unless they went for full DDoS and completely shut the sites down, but for semi-legit spam (that is, spam advertising something like a gambling or porn website as opposed to phishing or whatever) it could actually work, since those people might acutally pay hosting bills instead of just using hacked servers. In either case, as much as it sounds like a bad idea, I'd LOVE to see it work. Burn, spammers, burn!