Millions of drivers across Canada have traded that folding paper map from the gas station for a GPS (Global Positioning System) navigation unit.Originally developed by the U.S. Department of Defense in the 1980s, GPS units, kept on a dashboard or windshield, communicate with satellites hovering above the Earth to pinpoint your location on the planet.

With built-in maps for all of Canada and the U.S. (and in some cases, other continents), GPS navigation units can help you reach to your destination with turn-by-turn visual and audio instructions.

Take a wrong turn? No problem, within seconds you'll be rerouted to your destination. GPS units can also recommend millions of relevant “points of interest” along the way, including hotels, ATMs, restaurants, gas stations and more.

But this is just the beginning.

If you're in the market for your first (or next) GPS unit, the following are a few interesting features to aim for.

Bluetooth

If your cell phone has Bluetooth wireless technology, and chances are it does, a GPS unit with Bluetooth support turns into a speaker phone for hands-free calls. Plus, you'll see the name or number of the person calling on the GPS screen before deciding to answer it or not. All major GPS makers -- such as Garmin, TomTom, Magellan, Mio, Navigon, LG and Sony -- offer models with Bluetooth.

Real-time traffic alerts

Avoid congestion caused by an accident, construction or rush hour volume. Many GPS devices can steer you away from these troubled areas if it can receive real-time traffic updates, in selected cities. If the GPS unit supports this feature, it might cost the user a couple dollars a month to use it, while some Garmin models come with free traffic updates.

Text to speech

All GPS units can give you directions (e.g. "Turn left in 200 metres") but many today with a "text to speech" feature will also say the name of the street for you, as well (such as "Turn left in 200 metres on Alphabet Street"). This is handy when streets are close together and you aren't 100 percent sure when to turn.

Multimedia support

Many GPS units today can accept memory cards packed with music, audiobooks, podcasts, photos and videos. Taking a long road trip with your significant other? You might want to download an audiobook, copy it from your PC to the memory card and then insert it into your GPS unit. Turn up the speaker and enjoy while driving.

Change the voice

Some GPS units let you record your own voice (or a child's) to replace the ones already included with the GPS. It can be fun to personalize the unit and hear a familiar voice give you directions. On a related note, all TomTom GPS units let you download optional voice packs from a handful of celebrities including John Cleese, Mr. T, Kim Cattrall, Curt Schilling, Dennis Hopper and Burt Reynolds.