Originally developed for the Military, GPS was introduced to consumers two decades ago, but it languished initially as a marginally useful service for gotta-have-it gadget freaks.

No more.

Figuring out how to fold maps is a problem of the past. Compasses are passe. Portable GPS devices, fitting into the palm of your hand or built into automobile dashboards, now bring Space Age navigation to the masses.

Most interesting, the technology allows for a slew of creative products George Jetson never dreamed of.

In increasing numbers, outdoor enthusiasts tote along relatively small, portable, and inexpensive GPS receivers. The devices can record the locale of a secret fishing spot for a return trip next year. Or they can guide you a destination as the Sun sets on the long and winding trail you've been hiking all day.

And the system works.

GPS is the only system today able to show you your exact position -- within roughly 6 feet to 20 feet -- on the Earth anytime, anywhere. It functions in any weather conditions. And beyond the cost of a device, there are no subscription fees or setup charges to use the service.

Even high-end backyard telescopes are guided by GPS now. Knowing its exact location and driven by an onboard computer and motor drive, a telescope can automatically find stars or galaxies and track them across the sky, while a skywatcher is left to simply enjoy the show.

Perhaps most interesting -- and somewhat controversial -- is the ability of GPS to track other people.

A company called uLocate Communications, Inc., based in Newton, Massachusetts, offers a GPS application designed to bring peace-of-mind to families. The new service enables parents to pinpoint their children's whereabouts, around the clock, using cell phones, the Internet, and the latest in GPS satellite technology.

The uLocate service works with cell phones that can establish and broadcast their own location in terms of latitude and longitude using GPS.

The coordinates are then translated, through technology provided by MapQuest, for viewing as a local map after logging into a secure, private account on a Java-enhanced cell phone or on the uLocate Web site.

"We recognize that more and more kids are clipping cell phones to their backpacks when they head off to school as parents face complicated family schedules and increased concerns over their children's personal safety and security," said Alan Phillips, CEO of uLocate.

"We find that parents will strike a deal with their children -- they'll supply them with a cell phone in return for enabling the uLocate service," Phillips said. "Or an individual may request the service for an elderly parent, two partners for each other, and so on -- for virtually any group or relationship where one or more members will appreciate the peace of mind knowing where their loved ones are."

A range of GPS applications are little recognized and appreciated by the general public, said Glen Gibbons, group editorial director for GPS World, based in Eugene, Oregon. They include GPS-based timing of telecommunications systems, including the Internet, Wide Area Networks (WANs) used by banks, landline and wireless voice and data communications, he told SPACE.com.

Gibbons said a growth area is location-based services building on the Enhanced 911 platforms in cellular phones.

A few years ago, a Federal Communications Commission directive called for all wireless carriers to be able to locate 911 calls made from cell phones.

Enhanced 911, as it is known, forces companies to begin offering improved location capabilities on their networks. The companies incorporate GPS into cell phones, PDAs and other devices, so that a user's position can be fixed. Police, fire, or ambulance services can track down the whereabouts of a distressed person in the event of an emergency.

Asked for examples of odd or surprising GPS uses, Gibbons offered a host of things:

• Tracking the flights of pigeons
• Physical training systems that measure performance against biometric sensor data (as in running or kayaking)
• Modeling ski slopes and skiers performance
• Advanced driver assistance systems for lane-keeping, automatic speed control

There seems no end in sight for novel and creative uses of GPS.

Take for instance SiRF Technology of San Jose, California. The company recently showcased CuisineMap at an international gathering of telecommunications experts. The location-based application enabled attendees to find good local restaurants during the meeting. CuisineMap provided a list of some of the finest restaurants in the area, sorted by proximity to the user. The application provided a virtual tour of restaurant choices, helping the user navigate right to the restaurant door of choice.

Like commercial applications, the scientific use of GPS has been a boon too.

"I think we are just beginning to discover some of the most interesting applications for GPS," said Randolph Ware, President of Radiometrics Corporation in Boulder, Colorado.

He worked early in the use of GPS to study deformation of the Earth's crust associated with earthquakes, volcanoes, and tectonic plate motions, and for atmospheric sensing.

Ware points to several GPS networks such as SuomiNet, funded by the National Science Foundation. Also there is the Ground Based GPS Meteorology Network (GPS-Met), sponsored by the National Oceanic and Atmospheric Administration (NOAA). The organization has been established to provide real-time measurements of atmospheric water vapor for research and daily weather forecasts.

But at the top of the list for odd GPS uses, Ware noted a small but growing number of people who use it to find unique points on the Earth's surface. These specific locations are otherwise undistinguished.

"Enthusiasts are visiting these spots, photographing them, and posting information regarding these locations on the web," Ware said. "There is considerable competition to be the first to visit these sites. I find this to be an amusing, if not odd, use of GPS."

For those who like the thrill of a high-tech underground adventure, there is Geocaching.

This involves hiding a cache filled with small prizes or treasures. The geographical coordinates of the cache are first recorded via hand-held GPS receiver. These coordinates are then posted to an Internet service, such as NaviCache.com. Often clues are provided as to the location of the cache.

This treasure hunt calls upon those with their own GPS device to try and locate the secreted cache.

The basic idea is to have individuals and organizations set up caches all over the world and share the locations of these caches on the Internet. Once found, a cache may provide the visitor with a wide variety of rewards. That could take the form of maps, books, software, hardware, CD's, videos, pictures, money, jewelry, tickets, antiques, tools or games. Preferably, such items could be wrapped in a way as to be protected from the elements.