Thanks for the feedback Nomad. I certainly agree that a common GUI system is severely lacking for games/3D development. Creating my own, however, was a huge learning experience that I would certainly do again if I had it to do over.
Here are some more screenshots of the editor (large):
Hallway Angled Tiles More Angled Tiles Angle Editor Entity Property Editor
The last shot showing the Entity Property Editor is a dynamically generated scroll list of GUI controls for entity properties. Every entity registers property controls that have an internal values bound to them. Upon selection a list of property controls are sent to the edit window where they are created into GUI elements and sorted into an editable list. Just implimented this and am rather proud of how it works.
I certainly hope I don't burn out anytime soon either, but I get the feeling that if I do it will be like a friggin supernova.