white_dune is a graphical VRML97/X3DV editor, simple NURBS/Superformula 3D modeller, animation tool, and VRML97/X3DV commandline compiler in development. VRML97 (Virtual Reality Modeling Language) is the ISO standard for displaying 3D data over the Web via browser plugins ("HTML for realtime 3D"). X3DV is the direct successor of VRML97. VRML97 and X3DV have support for animation, real-time interaction, and multimedia (images, movies, and sounds). white_dune can read, create, and display VRML97/X3DV files and let the user change the scenegraph/fields. It also has support for stereoscopic view via "quadbuffer"-capable stereo visuals, and support for 3D input devices like a joystick, spaceball, or magnetic tracker.
PCity is a procedural city generator. It uses a configuration file and few maps (e.g. population density or a height map) and can be tuned via various parameters. Its features include street network generation, building generation, texture generation from a texture library, and a visualization engine.
FreeSG is a portable, high-level 3D engine with an emphasis on generality. It is designed as a component to be integrated, as opposed to an application framework. Its goal is to support applications ranging from small 3D games running on portable consoles to large simulations that must be rendered photorealistically using fourth-generation graphics hardware.
FreeCAD is a CAx RAD based on OpenCASCADE, Qt4, and Python. It features some key concepts like Macro recording, Workbenches, and the ability to run as a server. It's also platform-independent. It is is fully scriptable and designed to be easily extensible; only the core functionality is embedded into the core libraries, but all further functionality like support of triangle meshes, CAM, FEM, etc. is implemented in extension modules. Normally, such a module is divided into an 'App' part containing the data structures and algorithms and a 'GUI' containing the graphical representation of data structures, dialogs, workbenches, etc.