We have a few admins (global rights): me, dz, foxdie, taim, tapjpa. As dz mentioned, we won't be adding people to this group unless I know that they are a solid member of the community, etc.
We have several moderators (rights to specific forums). If people want to be added as a moderator to one or more forums, please just send me a PM. If I don't know you already, I'll look at your history on the forums.
With regards to the spam we get... by the time I get on the forum to check the spam it's usually in the trash can already. From there and admin either suspends or deletes the member and put their member name and IP address in the ban list.
The forum already has email validation in place (you receive an email and have to follow the link to become active and be able to post). I don't see the benefit of having admins approve new members as we won't know if they are spammers until they actually post.
I will look into the keyword filter and quarantine option... I think that's a great idea.
Thanks for the feedback.