GPS units taken on the trail several years ago provided direction and a simple map. Sometimes they included useful terrain features. Today’s GPS receivers have become true Personal Navigation Devices, and much more.

All but the most specialized units provide extensive maps, many with 3-D views of your immediate surroundings. The Magellan Roadmate 1470, the Garmin nüvi 855, the TomTom XL 340, and many others do this superlatively. But they also offer features that make your whole away-from-home experience better, like voice commands and text-to-speech directions, dynamic re-routing when you make a wrong turn, needed lane change or upcoming exit advance notice, and more.

The specialized SkyCaddie SG2.5 Golf GPS provides pre-loaded, detailed views of dozens of golf courses, and you can download many more. The Suunto X10 Military GPS watch provides an entire PND combined with an altimeter, barometer, thermometer and much more in a package that fits comfortably on your wrist. It makes an adventure trek infinitely easier.

Less specialized-application GPS units, like the Garmin GPSMap 478 or the Humminbird 383C Combo - designed for marine environments - provide an enormous range of features.

The 383C, for example, combines a GPS unit with sonar to make underwater surface features visible and fish finding easy. It also provides views and info on hundreds of nearby land features like marinas, coastlines, channel contours, and so forth.

The 478 can be used in either marine or auto situations with equal efficiency. It provides dozens of BlueChart g2 maps for marine use - coastal areas, inland lakes, and more - but comes with a City Navigator system that works as well on land as any other auto-oriented PND.

In the area of auto GPS units the globe is the limit. Apart from those mentioned above (the Magellan, the nuvi, and the TomTom) the Navigon 7200T is a stellar competitor. The Garmin Zumo 550 can also be used in your car, but really shines when you mount it on your motorcycle.

Get away from the water and the city into the wilderness and you’ll want to take along any one of dozens of outstanding outdoor GPS receivers.

The DeLorme Mapping PN-40 Earthmate makes a stellar companion in the mountains and along the trail. With its up-to-the minute-design dual processors and outstanding software you’ll never wait for directions. Long battery life and a high-resolution screen ensure that you’ll have no trouble reading the huge amount of data it can provide.

The Garmin Oregon 400T is a favorite among geocachers, outdoor types who love to hunt for planted treasure just for fun. The unit-to-unit data-sharing feature comes in really handy in that situation. In that hiking and climbing scenario, you also need a sturdy unit with every conceivable feature GPS designers have devised. The 400T delivers more than you’ll use in a year of daily use.

Your intended use for a GPS receiver might be in a car or on a motorcycle, mountain bike, boat, or just on a stroll along a mountain path or city street. Whichever, you’ll find a Personal Navigation Device that provides hundreds of easy-to-use features. With the addition of MP3, Bluetooth support, XM radio, and more, many of these units are well on the way to becoming indispensable all-round digital assistants.