Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Pygame - Pygame is a set of Python modules designed for writing games.
Sculptris - Sculptris: Enter a world of digital art without barriers.
Unigine - Unigine Engine is a proprietary cross-platform middleware, developed by Unigine Corp.
Misfit Model 3D - Misfit Model 3D is a 3D model editor that basically operates with triangle-based models.
libtwo - All-purpose c++ app prototyping library, focused towards live graphical apps and games