Augmented reality iPhone app

This kind of "augmented reality" application makes it hard not to own a smartphone: it shows you on the screen where to find the nearest subway station and how far it is away. Also, if you point it down, you see the actual lines running around you. It's nifty and exactly what you need to get around in places you are not familiar with.

'Nearest Tube' Augmented Reality iPhone App: Science Fiction in the News