Erm…it seems that these geeky folk have gone and created the Augmented Reality Quake system (Arquake) which will allow you to play the 3D shoot ’em up game Quake through a sort of virtual reality headset coupled to a GPS satellite tracking system. This means that you can walk around your neighbourhood shooting monsters and the like with your special virtual gun.
It’s a research project at the moment, but if this catches on it could play havoc with the sidewalks and bus stops of the world. More here too.