I found this link and have added it to the footers of all of my sites using very nondescript links:

Quote:

This directs spam harvesters to a page where their databases will be filled up with hundreds of randomly generated email addresses of the format velgktabat@zsmfebkpclktsks.com. This will cause them to constantly have to clean out their databases.
In fact, the page actually causes the harvesters to go through an infinite loop.

I know this is a stop-gap measure and that someone could filter out any links to http://www.hostedscripts.com from their robots. But hopefully it will disuade people from engaging in this nefarious practice.