Google Maps on iPhone - it's best kept secret!
I was mucking around with Google Maps on my iPhone the other day and accidentally double clicked the little triangle in the bottom left and found a piece of functionality that I had no idea was there. In effect it acts as a compass and moves the map round according to the direction you are facing. This is really handy especially when you are on foot navigating around a city for example.
It reminded me of the scene from friends in London when Joey gets into the map. See the screen shot below: