Custom User Ranks

[J. Thomas Jeans]

On a previous vBulletin forum that I was a member of, it was possible to assign not only a Custom User Title, but a Custom User Rank as well. I'm assuming this was enabled via a hack or a plug-in, but I can't seem to find such a hack/plug-in anywhere.

I'd greatly appreciate it if someone could help me work out how to make it possible for users to assign their own User Rank through the User CP.