Open Source Solid Modeling CAD
BRL-CAD is a powerful cross-platform constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing for rendering & geometric analyses, network distributed framebuffer support, image & signal-processing tools.
decida is [de]vice & [ci]rcuit [d]ata [a]nalysis. It is used for electron device characterization, procedural simulation/analysis of electronic circuits, or more general data analysis tasks.
A beginners' level theorem prover project for logic students. Okitsune is written in Haskell and open for contributions.