3D File format viewer/explorer
XNA based game engine completely written in c#
PHIGS (Programmer's Hierarchical Interactive Graphics System)
shader editor
A world editor for HGE game engine written in python and uses OpenGL.
an interactive 3D viewing program
A cross-platform game framework based on OpenGL and GObject.
Gimpel3D - 2D/3D Stereo Conversion Editor
3D game engine for C and C++
3D world editor for game development