Cross platform (lin/win/mac) geographical information system (GIS)
Open Source Routing Machine - C++ backend
Automated detection of the unknown early map projection
LaMa - A Localization and Mapping library
A GUI for the freeware Geographical Information System PCRaster
Plugins for OpenCPN
Google Earth Enterprise - Open Source
Geodesy based library (geodetic and geocentric functions)
HistoryLoc is a practical system to track place names over time.
A gui for linux users of miniHomer, a GPS tracker
In-flight navigation (and more) for private pilots (Linux).
GPSBabel converts and transfers data like waypoints, tracks & routes.