GPSDrive

"GpsDrive is a car (bike, ship, plane) navigation system. GpsDrive displays your position provided from your GPS receiver on a zoomable map. The maps are autoselected for best resolution depending of your position and can be downloaded from the Internet. Speech output is supported via the "speech dispatcher" software. All GPS receivers supported by gpsd should be usable"

Filling a gap between commercial software and the people is GPSDrive is this free and open source gem.