I've reimplemented CAPTCHAs (Wikipedia entry) for people wanting to leave comments. Basically, a CAPTCHA is one of those pictures of a random string of characters that users have to type in to be able to leave their comment, based on the fact that people are pretty good at reading these things, while computer programs aren't, so it should eliminate comments from automated spam programs. I think I've figured out my mistake from the last time I tried to do this - that time I only included the CAPTCHA code on the entry pages, but not on the comment preview pages, so when people were previewing their comments and then hitting submit, they were getting tagged as spam. I was sure to inlcude the CAPTCH code in the comment preview pages this time, and I've even checked it out with some test comments, so hopefully it will work right this time and all legitimate comments will get through.
I didn't want it to have to come to this, but spam comments had just gotten horrendous in the past couple weeks. Since I'd removed the CAPTCHA, I had been getting, on average, less than one spam comment per day making it through my other filters. That was pretty easy to stay on top of, and it wasn't cluttering up this blog. Recently, however, those comments have been through the roof (yesterday, for example, 27 made it through). Since my blog is set up to send me an e-mail whenever I get a comment, those spam comments weren't just cluttering up my blog, they were cluttering up my inbox, as well. Monday mornings, after a long weekend, were especially fun.
So, spammers, thanks for making everybody's lives more difficult. Jerks.