When you unexpectedly need driving directions or you have to find the nearest hotel, chances are you won't have access to a map or a guidebook. How about getting the information from your cell phone? Several companies are offering innovative ways to bring navigational tools and location-based directory listings (such as restaurants, gas stations, and movie theaters) straight to your phone--all in real time via the Global Positioning System. What's more, the services cost less than stand-alone in-car GPS devices.

We tried out three of the newest services: America Online's MapQuest Find Me, Gate5's Smart2go Mobile Navigator, and TeleNav for Research In Motion's new BlackBerry 7520. MapQuest and TeleNav operate only on GPS-enabled Nextel phones; Gate5's Smart2go is not tied to a carrier and functions on Bluetooth-enabled Symbian Series 60 phones (such as the Nokia 6600 and 7610), Microsoft Windows Mobile phones and PDAs, and the PalmOne Treo 650 and Tungsten T3.

Both TeleNav and MapQuest Find Me use Nextel's Assisted GPS technology to pinpoint your cell phone's location, allowing you to find businesses in close proximity and get maps and driving directions. TeleNav gives graphical and audible turn-by-turn directions, while MapQuest has only graphical and text-based information. (TeleNav has existed since early last year, but it's the first vendor to offer GPS service on a BlackBerry handheld.)

MapQuest has a Web feature by which people you authorize can track your location. The service costs $4 a month, or $6 monthly if you don't have Nextel's data plan. TeleNav is $10 a month on top of Nextel service. To get either GPS service, you download it to the phone as an additional app.

Gate5's $349 Smart2go setup is more complex. First, you need a phone equipped with one of the operating systems listed above, Bluetooth (to transfer the GPS signal from the supplied GPS receiver to the phone or PDA), and a memory card (to store the supplied data, including Tele Atlas maps of the United States and Canada). Then you transfer the information using the supplied card reader.

To identify the phone's location and acquire the spoken driving directions, Smart2go looks for the Bluetooth signal from the GPS receiver and transfers the info to your handset. The application helps you find points of interest (including museums and shopping centers), and provides reviews of places such as bars, cafés, and restaurants.

In our tests, TeleNav using the BlackBerry 7520 and Nextel loaded maps and directions relatively fast. But Smart2go on Nokia's 6600 and T-Mobile, and MapQuest Find Me using Motorola's i830 and Nextel, were sometimes slow in loading information. In addition, Smart2go's driving directions and maps were sometimes off by a few streets; a weak GPS signal may have been the problem, the company says.

On all three services some of the listings are out of date, supplying information about restaurants that no longer exist while omitting entries for newer establishments. And compared with the detailed maps displayed on dedicated in-car GPS setups (such as Garmin StreetPilot or Magellan RoadMate), the mapping info on these services is spartan. The small screen on a cell phone or PDA is partly responsible for the limitation.

It was sometimes difficult to find commands on Gate5's Smart2go and on MapQuest Find Me. Granted, the phone design takes a share of the blame. Despite such drawbacks, however, all three services prove useful for getting driving directions and for finding local businesses, regardless of whether you're traveling or in your own town.