I'm getting really tired of people registering and posting spam to our forums [ probably like everyone else here

].
* I've already enabled reCaptcha, which helped a lot with bot registration.
* I also implemented a promotion system which seems to work well at preventing linkspam in signatures.
Spammers still register for accounts and post new spam threads in the various forums. I solved this problem on our wiki by requiring manual account verification using an extension:
http://www.mediawiki.org/wiki/Extension:ConfirmAccount
So my question is this: is there a plugin or configuration option to do the above with vBulletin 3?