GPSBabel
GPSBabel is a cross-platform, free software to transfer routes, tracks, and waypoint data to and from consumer GPS units, and to convert between over a hundred types of GPS data formats. It has a command-line interface and a graphical interface for Windows, OS X, and Linux users.
GPSBabel is part of many Linux distributions including Debian GNU/Linux and Fedora, and also part of the 'fink' system for getting Unix software on Mac OS X.
Applications
Many contributors to OpenStreetMap use GPSBabel to convert GPS track data from proprietary formats to the GPX format OpenStreetMap requires.
GPSBabel is popular in the Geocaching community because it enables people with incompatible GPS units to share data.
GPSBabel enables owners of many different brands of GPS units to view their GPS data in several popular consumer map programs, such as Google Earth and Microsoft Streets & Trips.
