Viking is a free/open source program to manage GPS data
GPS log file viewer and analyzer
Build your own GPS unit
... the open-source glide computer
Simple GPS tracking server
Open source system for GPS tracking devices
Minimalistic wide-open GPS-locator/tracker
NMEA 0183 library for Java
Plugins for OpenCPN
A C library for parsing/normalizing street addresses around the world
A library to generate short codes
A reference implementation of the Polish geobotanical grid
GPS mapping and management software
Open Source Marine Chart Plotting Program
This is a port of LibRTK on C#, and into a small c/c++ library.
A tile-based map viewer with support for GPX files.
Toolbox for geoscientists and geo enthusiasts
Scientific research work of Francesco Montorsi,Univ. of Modena, Italy
A gui for linux users of miniHomer, a GPS tracker
FAA digital chart viewer for iPhone and iPad
A library for Ublox serial message parsing
a free and open map of wireless communicating objects