Forget about asking for help at gas stations. Your cell phone is rapidly becoming a one-stop source of directions. Over the past year, several startups have launched services that send directions to your phone's screen and provide a speech interface that reads them as you drive.

In most cases, these services require location information from a separate Global Positioning System receiver plugged into the phone. A lost driver dials up the service, which interprets a spoken description of his or her destination, calculates a route based on the GPS coordinates, and transmits directions back to the phone. New versions eliminate the external GPS receiver: gpware of Menlo Park, CA, plans to introduce a device this summer that includes a GPS receiver and cell-phone technology in a personal-digital-assistant-sized case that can be mounted on a car's dashboard.