admin approval plugin that integrates with JFBC

Andrew,
I'm a bit confused as to what you mean.. but there are 2 ways to do what (I think) you're looking to do in Joomla 1.6+ that JFBConnect supports:
1) If you really want to 'approve a user before they register', I'm assuming you mean you'll create the user on your own (and vet the user beforehand in some way, like for a club). In this case, you simply turn off User Registration in Joomla's Global Configuration area.
2) If you want the user to register, but simply want to be able to approve them before logging in, that's pretty simple too. In the User Manager, hit "Parameters" (I think), and there's a User Authorization setting (or something similar) with a setting like "None", "Email", and "Admin". Set that to admin, and after the user registers, you'll get an email which you can use to approve the user.

Hope that helps, but if I'm missing something, let me know!
Alex

No problem. If you're going the #2 route, just make sure that you have the "Skip Joomla Activation" setting in JFBConnect disabled.. otherwise, it won't work

Either way, let us know how that goes, and if you need anything else!
Alex