Viking is a free/open source program to manage GPS data
GPS track editor for editing tracks and planning (multiple) day tours
Create, edit view GPX tracks (in the background - online maps)
Plugins for OpenCPN
A library to generate short codes
Toolbox for geoscientists and geo enthusiasts
NMEA libary for java (protocol of GPS devices)
Customization of OpenGTS look and feel
Visualize data from the opencellid.org project
In-flight navigation (and more) for private pilots (Linux).
compeo++ - Manage Flytec/ Bräuniger Instruments