I was thinking while I was here at work, it should be entirely possible to symbolically link the skin files for the main menu to a directory on the SD, so as to make every SD stand out as a different menu. I can't try it out right now of course, but I plan to give it a try tomorrow, when I have a day off. I understand it's not exactly a "breakthrough" thing, but for me, it is an easy way to distingish SD from each other.