This isn't exactly the same sort of thing but here goes
I've seen a screen fitted into a hole in a case, which acts as a secondary monitor showing the Media Player all the time, or showing visualisations.
For example, you could set it up to be playing a game on the main monitor, but yet on the little monitor on the case you could still have the desktop showing. I have seen this being done, yet I don't know how you could do it. Rather kewl though