If you are in China which way is USA? North? West? The answer is roughly straight down through the earth.
This app enables you to visualize where are places on earth through a 3D globe interface. Watch how the north pole is not strictly straight to the north and how far it is (if you can travel through earth). The app matches the virtual globe with your phone orientation on earth which means, where you are pointing your phone is pretty much where the place is. Its kinda like Augmented Reality where you move your phone around to see the places.