http://www.alice.org/
Now this site you dont actually create objects, but you can drag and drop various ones onto a terrain and there are motions you can add to each object and create yourself a scene. I just started my first class a week ago so i dont know much about this program but so far i was impressed. There is a tutorial when you load it up that gives you the basics. I suggest downloading 2.0 instead of 2.2 cause its practically the same but with a lot less memory usage.

Oh yeah and this was made by grads from Carengie College so there might be bugs. Enjoy and let me know what you think or discover!