wrightmat -- I understand, it just felt a bit game breaking -- but as I described, I haven't played it enough to know for sure! Thanks for the reply!
Christopho -- Here's a few steps that will probably help:
-- Remove the SMF / Simple Machines Forum footer that is added to each page. Generally, spam bots will scan for these chunks of data w/ the version, and exploit particular issues with them.
-- Change the form design on registration (field names, etc) and make sure to update the PHP as well. Generally these scripts are written to grab specific IDs or element names out of DOM, and if they're different, they will fail.
-- Institute recaptcha instead of the SMF captcha.
A lot of other boards will tend to hold all messages by new members in a moderation queue, and once approved, the member's account becomes "unrestricted", e.g. no captchas and what not.
Not telling you how to run the forum, but I do have quite a bit of experience in handling sock puppet accounts and spam in packaged bulletin board software (phpBB/vBulletin/SMF/etc). So hopefully that will help out.