I had my first CHINA SPAM BOT INVASION upon opening the site for members to join.
wow that was fast that was quite an experience for me never again I hope never again
Well, EMail verification, CAPTCHA, and Stop Forum Spam (all stock features in the UBB, now) will kill a LOT of the spam registrations that you'll see coming by.
I believe id242 has a ReCaptcha modification on one of his forums that I'd love to see released into the wild.