This is a list of anti-spamming scripts available and a few details for each.
I've had good results on several wikis I administer with a small patch to UseModWiki which counts the number of external links before and after the edit, and redirects you to a page explaining the spam protection scheme in effect if there are four or more external URLs in the newly edited version of the page. This behaviour can be inhibited if you're logged in, or coming from a specific IP range. Mail me if you want a copy. -- DonaldGordon
This is similar to SunirShah's ShotgunSpam patch for UseModWiki.
RachelStruthers' script: http://www.otug.org/otcgi-bin/wiki.pl?RachelStruthers . Also for UseModWiki.
An AntiSpamBot is in development for use on this wiki only.