Was just passing by and noticed this news post. I clicked on the register link and it looks like you're using SMF's default CAPTCHA. I'm pretty sure this has been cracked by spambots already. You might want to check out the reCAPTCHA plugin for SMF. I've had zero trouble since I installed it a few months back on my comic site. Then again, wouldn't be much help if you think you're getting human spammers. Best of luck.