FlightGear Flight Simulator: free open-source multiplatform flight sim
An interactive viewer for three-dimensional chemical structures.
Open Source Solid Modeling CAD
3D Without Boundaries
Xj3D is an open-source Java codebase for the X3D Graphics standard.
3D .NET engine for Windows, Linux, Mac
Real-time 3D visualization of space
A Lightweighted Toolkit For Volume Rendering
Game engine supporting many 3D/2D formats and graphic effects
A simple web interface for Blender, for rendering animations..