GPSRouteX is a full-featured, auto-sequencing GPS route navigation application for Mac OS X. Full support for GPSd, import/export Google Earth KML files, import/export GPX files, create your own routes and waypoints, even use your laptop with Google Earth driving directions to give you spoken, "turn-by-turn" driving directions! For a more complete description, check out the feature list.
Mac OS X 10.4 Intel
Mac OS X 10.4 PPC
||Mac OS X 10.4 or higher GPS unit