I've done what mamewah mentioned.
Here's an older version of my skin (I know it's somewhat difficult to see clearly):

The list on the right is a part of the emulator-specific background images, so that "Arcade" is highlit when mame is the active emulator, and "Nintendo" when the NES emulator is.
Up and down on the player 2 joystick are mapped to previous and next emulator, and the effect is that you appear to scroll through the emulator list when changing emulators.
This is a bit of a pain to setup the first time, but a collosal pain for maintenance later if ever you want to add/remove/reorder emulators. Additionally (for me, anyway) number of the images for individual PC games and video files also have bits of the background in them to emulate overlapping objects and transparency effects, and this only compounds the maintenance problem. </rant>
I personally like the idea of selecting a platform, and then a game. There was a beta frontend I was fond of called sigTV (
thread |
site) that did have top-level emulator selection, but the site appears to be gone.