Once the domain of the military and mariners, GPS satellites have been available for consumer use for many years. I can still remember when the first ones hit store shelves, and many people wondered who would be interested beyond recreational boaters or hikers. Well, it didn't take long before companies steered toward the really big market: cars. (Of course, keep in mind if you do buy a handheld GPS, it can be used anywherenot just in your vehicle, though some are a tad bulky for walking around.)