Panda3D is a game engine, a framework for 3D rendering and game development for Python and C++ programs. Panda3D is Open Source and free for any purpose, including commercial ventures, thanks to its liberal license. Go ahead and grab it here. To learn more about Panda3D's capabilities, visit the gallery and the feature list. To learn how to use Panda3D, check the documentation resources. If you get stuck, ask for help on the forums, our community is very active.
Great engine! :D
Not only is it simple and easy to use, especially with python, but the community is the greatest. :D Most helpful group of people I have seen in an online community. :P