gosmore is a program to view, search, and route
using openstreetmap data. It includes many features, like acquiring the current location from a GPS receiver, turn-by-turn navigation, and recording of tracklogs in GPX format.
Navit is a modular, touch screen friendly car
navigation system with GPS tracking, a real-time
routing engine, and support for various vector map
formats. It features GTK+ and SDL user interfaces
in addition to a GL-accelerated 3D view.