Is there an add-on available (or is it possible to make one) that allows you to make a skin and have it imported and placed in the game to be used as visual enhancement for your interface?
I don't mean simple box textures or a single bar like Titan Panel, but something that has the potential to be a full-screen decorative object which you can configure your other add-ons to fit around.
Here is a basic image of what I mean:
Obviously I would alter the textures size and different shapes to be used so as not to obscure the world view as heavily as the image shows (it's just to show the basic concept). Seeing the Blizzard Art for the default UI (like the action-bar) makes it seem this kind of thing is a possibility.
One could make so many wonderful interfaces if this was possible.
Edit: Another example image that seems to actually be implemented: