It would be interesting to have an app that tilted your screen to see what it would look like from other places on the globe. I'm sometimes curious about the angle offset I have with various other parts of the world.
Though you'd need to be able to rotate in two dimensions to properly capture the differences on a globe. It might be able to, if it's rendering the desktop to a 3d surface and applying the rotation to that.
Actually, even cooler would be to have an actuator that would physically rotate the monitor around all 3 axii instead of rotating what it displays.