I'm searching for a plug-in that will allow me to grant my blog authors the ability to manage user roles. But I need to restrict their ability to grant Admin role to anyone. Basically, I don't want them to be able to grant role permissions above their current role.

I've tried "role manager" but when I allow my author the ability to "edit users", the author can then change the role of the Admin as well. That's not acceptable.

Please reply if you have a solution for user role management only below their current role.