Wikitude and Layar are two lovely apps for your mobile. Both of them use your physical location and provide information about what is in the nearby including Wikipedia pages, Images from Panoramio, Videos from youtube and many other additional layers.
The only thing that is missing is a layer with the Facebook pages describing closer places or closer shops. I believe that this application can be useful to monetize in the mobile world. If I am in a mobile environment my location is my query. There is no need to submit a query based on keywords to get some information in return. Similarly, there is no need to subscribe a feed. I can just use my location and get what is interesting around me.