Back in the late 1980s the Magellan Systems Corp introduced the first handheld satellite-navigation device for consumers, which tapped the U.S. Defense Department's Global Positioning System—the same one used by the Pentagon's fighter pilots and Special Forces commandos—to pinpoint the user's location anywhere on Earth. It was a revolutionary development for everyone from backpackers and yachting enthusiasts to vacationers trying to make their way around unfamiliar cities.

Three decades later, once exotic GPS is now a stock feature in iPhones, iPads, Android devices and other smart phones and tablets that are also equipped with Internet access.

Now the combination of GPS and Internet access with digital photography, maps, social networking, language-translation software, and augmented