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.
IGE is a pre-visualization ("previs") tool for film directors.
TclMagick is a Tcl interface to the ImageMagick library. *NOTE* - it is now officially part of the GraphicsMagick project! Look at the projects home page for more information.
Lamia or Lamia Engine is the modern generation free distributable and open source game engine for creating computer games for several prevailing software platforms and very maybe hardware platforms either.
Extension for Tcl, which provides a complete new implementation of a graphic system for Tcl similar to Tk but on a new basis with an abstraction layer inserted to be able to use different physical graphic systems like X11, cocoa etc. easily.