Yesterday I noticed that I was having a comment spam problem. A few low-life moron ishholes have been using my blog to try to increase the PageRank of their various businesses: search engine optimization, porn, and cheap prescription drugs. The links were to free blog hosts, which in turn redirects to their crappy pr0n sites.
I found this Killing Comment Spam Dead posting, which contains some very good ideas and pointers to prior art, such as queuing submissions, url matching blacklists, form tricks, and a discussion of why most approaches suck. For .Text I have discovered you can add a list of domains to ban, and add a trigger to the content table to delete a record for inserts if the text has a link that is in the banned list. This has some caveats, but I think I'm okay with that for now. We'll see how persistant they become.
UPDATE: I found a component for .TEXT blogs linked from this article: CAPTCHA Image Control for .Text available which links to Miquel Jiminez
New version here for Clearscreen CAPTCHA Control v1.4 Released with Community Server 1.0 support [UPDATED]