Just wanted to announce, that I've created a basic scene graph, which allows creating OpenGL programs interactively (supported languages are Delphi, C++ and Ansi C).
You find it at
The process works as follows:
You create a scene in Carad, a 3D content creation program, and save it as project in your favoured programming language. The saved project can be compiled at once, and you can work with the exported source to expand it easily to a full fledged application (for example a demo or game or whatever).
Carad compiles against the BaseGraph library, which is provided as full source. Projects may be created for Win32 environment and Linux (using GLUT).
By the way: on http://www.basebraph.com you'll also find an Open Source version of a predecessor of Carad.