Take Gled (http://www.gled.org/ - a recent CVS snapshot is preferable), a distributed C++ application builder with OpenGL/OpenAL/FLTK interfaces, object persistence and excellent extensibility.
It certainly is not pretty the first time you look at it, that is probably true for any unique project, but if you look harder, you will see a strange tangle using ROOT, CINT the C++ interpreter, built-in C++ object dictionaries, elegant and fast network stack for object streaming and synchronization, and strangely effective remote procedure call interface. But my favourite is the auto-building FLTK gui.
While remotely involved, I do enjoy this code immensely.
Try building a new library for it and enjoy GUI-enabled objects in minutes... (There is even a scratch for a TA-like game in one of the demos, not yet playable.)