TomTom, the GPS manufacturer, has a new idea to keep you going in the right direction. In an industry first, the company is now offering an online downloadable map update service for its navigation devices.There are two update plans available. You can update the maps inside your device once a year with any worldwide map for $79.95, or sign up for the one-year map Update Service, with the ability to download new maps four times a year for as little as $39.95. The actual final cost depends on the age of the map currently installed in your device and the maps included in the service type you choose. You accomplish the upgrade by signing up for the service, installing special TomTom Home software on your Apple ( AAPL) Macintosh or Microsoft ( MSFT) Windows computer and connecting your GPS box to that computer. The service will tell you if you have a new map waiting. The company warns that once you have purchased its online Map Update Service, it cannot be transferred to another TomTom GPS device. You can buy map updates for industry leader Garmin's nuvi GPS devices from retailers nationwide. The 2009 North America map DVD retails for $69.99. You can also buy a "Lifetime North American Map" subscription, which lists for $119.99, and is valid for the life of your Garmin GPS device.