Using SpamAssassin and friends seems to have chopped the amount of SPAM I see somewhat. Still a lot of it gets through anyway. The spammers just get more and more clever sliding the stuff past the filters.

I've even given some thought to how I could write an accounting script to calculate the amount of CPU time that is spent by my mail server processing it and billing the spammers for their share of what it costs to filter the crap out. When they refuse to pay take them to small claims court (keep the $$ amount below US$5000) and sue them. If they still don't pay take a lien out on their assets starting with any computers they use to send the stuff.

Probably wouldn't work out in real life but hey... it's a thought....