User controlled Usergroup

[Sykoi]

This is a mix between a request and a question.

Is there a hack out there, that allows you to set an owner to a usergroup, so they can add new members themselves? If not, would someone mind pointing out a few of the functions I'd need to use to make this (Usergroup functions) - or even what file these functions would belong to?
I can write it myself, and will post it on vb.org - but only if I can get some help with vB's functions


Thanks in advanced