Offers down-to-earth guidance for hikers, cross-country skiers, ATVers, and other outdoor enthusiasts who own or are thinking of buying a GPS receiver, as well as people interested in digital map-makingGPS (global positioning system) receivers draw on satellite signals to precisely determine a person's geographic position; as prices for these devices have gone down-entry-level models now sell for $100-sales have risen dramaticallyProvides coverage of the increasingly popular sport of "geocaching," in which people hunt for a canister hidden at precise geographic coordinatesExplains how to turn cell phones and PDAs into GPS receivers and what hardware is required for connecting a GPS receiver to a PCShows how to use popular, inexpensive software packages to create topographic, aerial photographs, and three-dimensional maps, and discusses free Web-hosted map servicesThe author's diverse background in archeology, outdoor rescue, adventure racing navigation, and dis aster response set him apart from other people writing about this topic