Approve new members..??

Hiya folks!

Is there a plugin which would allow a network admin to hold all new member signups for approval?
My site recently was over run with sploggers... it was harsh. Now I've enabled Facebook loggin, but I don't want to restrict people to the facebook loggin - so I want people to be able to login without having facebook accounts.
The problem is - I would like the ability to "approve" new memberships that didn't use facebook.

Any suggestions? Ideas? anything?