Invite system hack

[ADiuM]

I would love to know if a mod like this is available, I've used the search engine and there was some talk about it before but it never went anywhere.

I run a private community and it all relies solely on my members inviting others to join, without an invite they can't join.

So kind of like the GMail system that google has.

It'd be great to tie it in with the Subscription feature in vB, basically all users get a set amount of users then can invite. It'll automatically generate a code and then they can give that code (or url with that code on it) to a user who has to enter the code (or click the url which automatically fills in that code) to register.

Once they've registered that code gets used up.

Subscription users can get even more invites then others or even an infinite amount of invites.

Is all this possible? I don't even know where to start in making this mod myself.