I added a hidden page to my site and linked to it from some of my other sites to inconvenience spammers a bit.
http://stormvisions.com/pages/spambust.php It links to other sites that generate random urls/emails and theoretically can clog spammer bots databases.
If anyone thinks it might be generally useful to create a module to generate a page like this then some things to consider
You should add a robots.txt file to disallow this page and/or folder so 'good' search engines that find that page don't block your site. Add the Google rel=nofollow parameter to all links on the page, use a separate template without your normal meta tags and links so as to not pull them into your real site content, and I'd propably add the
<meta content="NOINDEX, NOFOLLOW" name="ROBOTS" />
<meta content="INDEX, NOFOLLOW" name="ROBOTS" />
to this template to again help good bots avoid this page -bad bots don't respect this anyway. In addition if the page could link to fake images, urls and emails -possibly to other sites that offer this as I have done- it might cause them to index an endless amount of fake pages and emails.
Here is a link to a php scrips call PHP Spam Poison you might find useful
http://www.mariovaldez.net/software/phpwpoison/ if you want to take a crack at this. I just built a page manually but figured I'd suggest it.