Easier Usergroup Change?

[alternity]

I run a vB install for a gaming clan. We use military ranks for members, and each rank is it's own usergroup. Now when people in the clan want to promote another they have to have access to the admincp and login to that in order to change the persons usergroup. I was wondering if there was a simple way I could set it so that members of certain usergroups would see a button in the postbit of a specific usergroup (the registered member usergroup) and when they click the button it'll put the user into a different usergroup.

It doesn't have to be eligant, but any way I can just hack this in easily would really help out our admin's from having to manually switch the usergroups of these people.

Also making the usergroups joinable is not an option, as we are reviewing people before letting them in.