What the Admin Skin module does
The Admin Skin module was designed to allow the site admin to set one skin for the admin area and another skin for the forward facing site content.
It was designed to be used in conjunction with the jrAdminMenu.
These two modules together allow the use of one site on the front end and an alternate one on the back end, complete with back end navigation.
It just makes converting existing templates to skins a bit easier.