There it is, that good old pale blue dot in all its earthly glory, right there on your computer screen. It's a familiar sight, even from a sky-high perspective experienced only by astronauts and angels. But hold on. By mousing around and clicking, you swoop like Superman, down, down, down, to a location on terra firma. Coastlines and rivers come into view, then cities, houses and even cars. And then, with another mouseclick, you can see the roads labeled, highlight the high-crime areas and locate the nearest Chinese restaurant. (The photography is provided by a combination of satellite images and pictures from aircraft flyovers.) If an alien flying-saucer jockey ever had an urge for chicken in black-bean sauce, this software would come in handy.

This particular Web-based program is called Keyhole and costs under $100. (Spy agencies used to spend millions for this, and they didn't even get the restaurant overlay!) But it's just one impressive product of many in an area marked by furious innovation. Digital mapping is about to change our world by documenting the real world, then integrating that information into our computers, phones and lifestyles. Roll over, Mason and Dixon: spurred by space photography, global satellite positioning, mobile phones, search engines and new ways of marking information for the World Wide Web, the ancient art of cartography is now on the cutting edge.

"The whole area of mapping is exploding in a lot of different directions," says Tom Bailey, an exec at Microsoft's Map--Point division. Millions of road-trippers download custom maps from Web ventures like MapQuest and Yahoo Maps. You can now Google things by location: type in a ZIP code and "laser surgery," and you'll find the closest places that can fix your vision. Carmakers offer GPS navigation systems as a built-in option; cell-phone and PDA users can find the nearest lavatory or pool hall; and a mobile application called Dodgeball lets you know if any friends--or friends of your friends--are within 10 blocks.

But just over the azimuth is the holy grail of mapping, where every imaginable form of location-based information is layered onto an aggregate construct that mirrors the whole world. "I call it the Virtual Globe," says Jack Dangermond, founder of Environmental Systems Research Institute (ESRI), a Redlands, Calif., company that pioneered what's known as Geographical Information Systems. "It combines the World Wide Web with geographical information like satellite images, roads, demographic information, sensors... and then you're modeling the planet as a living system."

Dangermond knows this turf well. When he started ESRI in 1969, geography was an uncool academic pursuit, and using computers for mapping was, well, uncharted territory. But at Harvard years before, he had been among the first to experiment in creating virtual maps that "layered" quantitative information from databases onto them. Though sometimes complicated to use, these efforts in "digital geography" were incredibly powerful, and were invaluable to customers in corporations (notably energy companies looking for an edge in exploration) and the government. ERSI's products were used, for instance, to find the best location for a new mining town in Venezuela and the placement of ski runs in Utah. But in the 1990s, Dangermond understood that ERSI's original model of a closed, proprietary system wasn't going to work when geographical information became widely distributed on the Web and routinely integrated into thousands of applications and services. The company spent $340 million to change its system to conform to open standards, to make ESRI's software open to developers who write what Dangermond calls "maps for your apps."

Of course, now that the mapping field is expanding from the traditional players to the mass market, Jack Dangermond's strategy pits him against Bill Gates. Microsoft's MapPoint division has 150 engineers, including many cartographers, creating simple ways for developers to put mapping information into their software applications. And, of course, Microsoft isn't the only competitor: a slew of major tech companies, from IBM to AOL to Oracle, "are all involved in a big way," says David Schell of Open GIS, a nonprofit consortium that promotes open geographical-information standards. "It's now one of the key components of the Net."

Adding a geographical dimension to an existing application not only increases its utility but sometimes produces a level of information that's downright scary. For instance, the Federal Election Commission's requirement for digitally logged campaign contributions hadn't really caused much controversy--until Michael Frumin, a researcher for a nonprofit arts-based technology firm called Eyebeam, decided to "geocode" the information-- assigning the precise latitude and longitude to the addresses. This allowed users of the Web site he set up, called Fundrace, to type in an address and see which candidates their neighbors were supporting, and how much they gave--you could virtually canvass the neighborhood to see who gave what. An extra bonus was that the contributions came with addresses that were sometimes otherwise unlisted. (There's Ben Affleck! And he gave to Dennis Kucinich?) The consternation of suddenly exposed donors may be a harbinger of complications to come when innovative mapping pegs hitherto obscure information to a specific location. In short, we're at the beginning of the age of geo-voyeurism.

We can soon expect even more powerful ways of extracting location data from everyday information. John Frank, the 27-year-old founder of a company called MetaCarta, has a method to "geo-parse" documents and files, extracting any mention of a place. (What's more, Frank says a location need not be an address or population center but "anything that's bolted down"--a physical landmark or even a fire-alarm box.) When the word "media" appears in a document, for instance, his software uses the context to determine whether it refers to the news business or one of the nine U.S. localities that go by that name--and if it's the latter, which one. Then it tags the information with the geographical coordinates. So when someone does a MetaCarta search for a town in Iraq, a stretch of roadway or an area rich in crude oil, it searches its hundreds of geo-parsed databases (including research papers, news articles and 800 million Web pages) to come up with every document that refers to that location. Right now MetaCarta's customers are mostly in government (it's funded in part by the CIA) but similar technology will probably wind up being common on the Web.

Clearly, we're headed toward the day when any reference to a place gets tied to the actual location--and vice versa, as GPS-equipped voyagers enhance their travels by accessing the secret history of the ground beneath their feet, as well as discovering what's on the road ahead. Because commercial databases only go so far in supplying that information, a number of independent, open-source-style projects are encouraging a participatory approach in providing digital annotations to the physical world. For instance, one project collects and maps interesting examples of graffiti in the streets of San Francisco. A scheme called GeoURL encourages bloggers to tag location information to their Weblog entries. (This allows people to keep track of what's going on in their area.) Eventually, between the databases, the parsing and the geo-hackers, millions of places will be digitally annotated, and the experience of traveling the world will be akin to visiting a museum with an exquisitely informed guide.

Companies like Keyhole hope to become the substratum upon which all this information is layered--fighting Microsoft, ESRI and others for the honor. (Keyhole CEO John Hanke boasts that it already has a program to allow amateurs to post their own layers to the maps.) Ideally, they'll all coexist: think of these supermaps as the equivalent of Web browsers yielding the world's knowledge through the lens of location. They'll spur companies and governments to make better-informed decisions and enrich the experience of just plain people as they take a walk through the city, hook up with their friends and hunt for Chinese food. These will be maps that change the territory.