Lately spammers have found my contact form and have been having a field day with it. In 24 hours from yesterday morning until this morning I got 127 ads for cialis, cheap cigarettes, and a host of other junk. It doesn't look like they were able to use the form to spam others from my site (thank you Drupal!) but it's more than a little annoying.
So now I'm experimenting with different means to deal with the issue. First up is the Captcha module. I've installed the current version recommended for D6, 6.x-1.0-rc2 and set it to use the text captcha on my my contact form and on the comments form (another area where spammers have been going nuts).
I also set Captcha to log attempts which it blocks. In the 9 minutes I've had it installed, it's blocked two already.
[edit 2009-06-04 17:50 EST]
Since this morning, CAPTCHA has blocked over 500 attempts to hit the comment form, all from IP addresses at 91.214.45.* The good news is that they're being blocked. What I don't like is that they're still using up system resources. So, I'll add that IP to the banned list and see what that does to the spam attempts.