I was getting spambot registrations at the rate of at least one per hour, and was having to continually monitor my site and delete them as soon as they appeared. I had recaptcha and opt-in email enabled for registration, but apparently they found a way past the controller. Anyway - I installed spambotcheck, and it is handling the spambots like a pro. I set it to registration only, and only check the IP. I've doubled checked several of the IP blocked, and they all have been from strange locations and are on spambot lists. Thanks for a great plugin!