GPS receivers are too expensive. The price point needs to be $100 instead of $300-500. At $100, everyone will buy GPS. Otherwise, they will wait until it is incorporated in every vehicle, computer, and cellphone as it will some day. The GPS manufacturers like Garmin could offset this lower cost by providing location-based advertising. When you get near a Starbucks, for example, the GPS receiver could display a small advertisement alongside your map with a special offer for coffee. It would be like AdSense advertising for presence.