GPSBabel converts waypoint data between about fifty file formats, including Magellan and Garmin serial, Garmin USB, Mapsource, Mapsend, Streets & Trips, Delorme, National Geographic, many PDA formats, and many others. It is endian and word-size safe, includes a GUI, and runs on a variety of operating systems. It also supports Groundspeak GPX extensions for geocaching.
These details are provided for information only. No information here is legal advice and should not be used as such.