[Plugin: Register Plus] Feature suggestion – Automated Invitation Codes

I really enjoy the Register Plus plugin, but there is one thing I’m missing to make it usable for my own WP instance.

The plugin currently offers an option that requires new registrations to enter an invitation code.

What I would like to do is to give certain member groups the right to invite other users, using a randomly generated invitation code.
So the only way to get registered on this portal is if you are being invited by someone else. Just like Gmail used to do that in the beginning.

I’d love to see such a feature added to this plugin

http://wordpress.org/extend/plugins/register-plus/