Child tracking is just one of a host of mobile-phone applications that use Global Positioning System technology. Other applications include those for tracking the whereabouts of friends, pets, and employees, and those that let farmers survey and navigate their land, hikers create routes and download maps, and skiers check snow conditions and reserve seats on backcountry helicopters. Although consumers have yet to embrace such products en masse, application vendors who follow market predictions are no doubt hopeful, with some research firms--such as Global Information--estimating a global growth rate of 9 percent by next year.