(I couldn't find this one doing a search, so I figure it's all right to start a new thread about it. ^_^ )
If you have your own website that seems to constantly get flooded with spam from web bots and the like, especially if it's a message board or guestbook or anything else that allows user interaction, I very strongly recommend looking at Project Honeypot (link below).
http://www.projecthoneypot.org/
What it involves, basically, is that after you register an account there, you download a special script code (called a "honeypot") that you then upload to your site and manually visit once to activate. Then you place code on your home page that allows a bot to visit but that a human visitor won't even see or know about. The folks running the Project Honeypot site then log visits to the honeypot you've uploaded so that they can hopefully track down the source(s) and any spam robots that visit your site so the proper authorities can then be alerted.
There are also some helpful tips on the site about how to keep your e-mail address hidden from spam robots and yet still visible to real human visitors.
Incidentally, thanks to Shooraijin for giving me the link some time ago. ^_^