Lots of talk on location based services the last couple of years. And always the same example of receiving a personalized coupon on your cellphone when walking past a McDonalds... But if you're really interested in understanding the potential of location based services, take a look at the how it's being used for mobile gaming. Especially the way 'augmented reality' is being implemented here can be very valuable to other industries as well.
"IN-duce:De-duce published a list for mobile phone games using GPS or cell towers signals, there's also a lists of other location based (or augmented reality) mobile games."