Alice

Alice is a free software program that can be used to create computer animation. Although that might sound complex, I was impressed at how easy it was to use. Its "drop and drag" nature made it very simple to select 3D models and begin creating a series of moves they would perform. This might be a great way to allow kids to tell stories or present ideas, while gaining a introduction into programming.
Here is a short example of a clip I created using alice.