1. A mobile navigation unit, comprising: a navigation computer configured to request, receive and interpret routing data comprising turn-by-turn directions for a destination from a navigation server over a computer network and to reconstruct a route from said routing data for display on a geographical map, said routing data describing said route, said route being based on real-time traffic data and pre-stored user profile information; a display screen configured to communicate with said navigation computer for displaying and updating a current location of said mobile navigation unit, a current bearing of said mobile navigation unit at said current location, and said route superimposed on said geographical map during navigation to said destination; a web browser interface configured to operate in conjunction with said navigation computer and said display screen; and a port configured to releasably connect an external device with said mobile navigation unit, wherein said navigation computer is configured: upon receiving one or more initial characters for a data entry field, to identify a set of conforming data items and to select one data item from the set of conforming data items as an anticipated data item for that data entry field, to use speech recognition for accepting voice commands, to automatically scroll said geographical map based on change in said current location, and to rotate said geographical map clockwise and counterclockwise in order to selectively change an orientation of said geographical map as displayed by said display screen.