LocFinder is a really well-made that uses augmented reality to lead us to a particular destination can be our car or a predefined location. Obviously its features are expressed at most 3GS iPhone but also works on other devices.

Above we see a compass indicating the direction to walk, and down instead we have a globe that shows the location of the destination and hence its distance to the point where we are. Clicking on the compass will open a new section where you will enter into action augmented reality that will lead us to a point in advance.