New GPS units not just for directions

— -- Millions of Americans have finally traded the folded gas station map in the glove compartment for a handy Global Positioning System unit.

You know, those small doohickeys that communicate with satellites hovering above the Earth to pinpoint your location. With built-in maps for the entire USA (and, usually, most of North America), GPS navigation units can help you reach your destination with turn-by-turn visual and audio instructions.

GPS also offers millions of relevant points of interest, such as restaurants, gas stations, hotels, ATMs and tourist attractions. And if you get lost, a GPS device will recalculate how to get back on track.

Now, a host of impressive features for these mobile gadgets make them work even better.

So if you're shopping for your first — or next — GPS unit, consider the following five features (many devices will have two or more):

Garmin Nuvi 660:

Real-time traffic alerts. New GPS devices can alert you to traffic issues so you can avoid them. But the service usually requires an annual service fee (of about $60 a year) to get the real-time updates. Plus, it's available only in select cities throughout the USA, Canada, Australia and New Zealand.

A small antenna gets data via FM frequency, so you can be warned of traffic backups. The Garmin Nuvi 660 ($749.99 at www.garmin.com, but you can find it, and other products mentioned here, for less if you shop around) includes this integrated traffic receiver and a 90-day free trial.

Mio DigiWalker H610:

Built-in battery. GPS devices once were limited to the vehicle where they were used, because they either had a non-removable in-dash design or required power from the car's cigarette lighter. Now, many GPS devices offer a rechargeable internal battery, which means you can easily use it in any vehicle — or even on foot. The Mio DigiWalker H610 ($199.99; www.mio-tech.com) is smaller than a bar of soap (2.32 inches by 3.35 inches by 0.74 inches). It also offers pedestrian and cycling maps, so it won't tell you not to walk the wrong direction on a one-way street.