Viking is a free/open source program to manage GPS data
SUMO is a microscopic, multi-modal traffic simulation.
Entrain your brain!
OpenGL Mathematics (GLM)
Computational Brain Imaging Group tools
For exploring cellular automata like Conway's Game of Life.
OpenGrADS provides extensions and interfaces for GrADS.
Model Railway CAD program
Library to control radio transceivers and receivers
Open source cross-platform Java Visual Traceroute
Open source finite element software for multiphysical problems
Real time satellite tracking and orbit prediction
TI graphing calculators <-> computer communication software
Toolkit for working with and mapping geospatial data
A web-based interface for CNC milling controller running Grbl, Marlin,
C++ library for half precision floating point arithmetics.
Open source Health IT for the planet