I bought the vinyl skin from here
http://www.vinylskins.com/colorskin-seg ... pular.html
They allow you to upload your own artwork to be printed onto their pre-measured decals. I uploaded the Karous logo from a wallpaper onto their pre-fab dreamcast measurements, but they offer skins for most popular consumer electronics, including game consoles, phones, laptops, etc. I think you could also supply your own measurements if you just want a simple rectangle.
I lucked out a bit with mine that the black background of the decal meshed well with the black plastic of my "sega sports" dreamcast. I'd give it some thought as to how the decal will look on the colored plastic or metal of what you would put it on since I don't think you have the option of doing a transparent background (you have to upload a custom image as jpg).
Otherwise, it's pretty good quality. Very glossy/shiny, and sticks pretty well.