Arduino command line tool
A circuit simulator with graphical user interface (GUI)
General Mission Analysis Tool
Open source Health IT for the planet
Open Source CFD Toolbox
Real Time Electronic Circuit Simulator.
Library to control radio transceivers and receivers
2D molecule editor
Tool support for the Z formal notation
Linux GPIB Driver package (source)
Astronomy CCD capture software
TimingEditor is a tool to graphically draw and edit timing diagrams.
A free GNU/GPL educational digital photogrammetric workstation