Wish to start the new year with an idea!
Last week when I was traveling in a train during night, wanted to find out where am I? The best tool I had was my mobile. Tried 'Cell Info', but found advertisements from the cell phone service provider or some location name which was difficult to identify (say like EB Bhavan, CHB colony).
How about having a "Where am I?" mobile based location service. Send a SMS request and you will get a short map with the cell location. For revenue purpose, the reply can include local hotels/restaurants (more like Google Map search).
This might not be as accurate as GPS enabled service. Since the location could be on the border of the cell or there could be overlap of the signals from different cells.