Two weeks after I disovered and integrated CFAkismet, my spam tally stands at 1, with no false positives. Before I added it in, I was deleting 100+ spam comments per day.
Akismet, the comment spam solution created by the people who brought the world WordPress, is an awesome concept: it works spectacularly well, and is not anywhere near as invasive as CAPTCHA routines. Shame that everytime I type the name I spell it wrong. Heartily recommended!