I got so sick of deleting spam off my website, I decided to install various Captcha modules to stop it happening. I've done a few quick tests, and they work far better than they did about 6 months ago. I've actually got a range of different, random captchas installed, ranging from ascii art, to phrase completion, maths questions, and missing letters. It does mean leaving a comment on my site is a bit like the Krypton Factor (for those of you old enough to remember that), but hopefully it will cut down on my spam (which was up to about 50 comments a day NOT being caught by the filters; upwards of 100-200 per day which were getting caught). I may even turn the spam filters off, as they always seemed to rate comments from my friends as spam, while letting through endless crap about viagra and porn.