Presselite has an iPhone app that combines information from google maps, GPS and the camera to give an augmented picture. The photo above shows a MacDonalds icon for the branch across the road. The image comes from a YouTube video that demonstrates the need for an anti-reflection coating on the iPhone. There was a time when my wife worked on military applications of this kind; the idea that you could just download them onto a phone was beyond imagining then.
Seero is a website for geo-broadcasting, which is an interesting development with lots of practical applications - the emergency services, for example.
However, my favourite is a mash-up by a Mr McQueen, of a car chase. He can drive, but has an odd spelling of Bullitt. Worth watching again just for the sound track. Purely in the interests of research, of course.