A version of the source I used in these videos on youtube: http://www.youtube.com/watch?v=5k6arok7zac http://www.youtube.com/watch?v=TaNu8-ObsXU and http://www.youtube.com/watch?v=7qAq61ATgqo . It requires Sunflow, JBullet, and Java.
GLUI is a GLUT-based C++ user interface library which provides controls such as buttons, checkboxes, radio buttons, and spinners to OpenGL applications. It is window-system independent, using GLUT or FreeGLUT.