I think the problem with this site is that there are so many guests hitting the site that are potential spammers!
Anim8orWorld have the honeypot project running on our SMF 2.0.2 site and the spammer level is on average 30 spammers a day, which are trapped and ejected before even getting to the forum, then registration is protected with stopspammer that reports any suspect and is held in hiatus until checked and verified by admin.
With the membership level here at over 6800 (of which the majority have not even bothered to post ) the spammers will again have a field day.
Between August 2010 and November 2010 6014 new registrations were made, all of whom, I suspect were spammers/Harvesters.
So my first objective, rather than to just open it up again would be to update the forum software to the latest SMF 1.1.16 or even better the latest 2.0.2 version and add a honeypot to the site as well as a stopspammer mod. Then to delete the 6000 odd bogus accounts that have been made.