FlightGear Flight Simulator: free open-source multiplatform flight sim
3D Engine c++
Open Source Solid Modeling CAD
Earth orbits and satellite coverage display in 3D on your laptop.
3D .NET engine for Windows, Linux, Mac
A simple and easy to use render farm for Blender
A Lightweighted Toolkit For Volume Rendering
Game engine supporting many 3D/2D formats and graphic effects