MakeHuman is an open-source human figure creator based on Python. It is free and runs on Windows, Linux, and osX.
Twine is an open-source tool for telling interactive, nonlinear stories.
Twine publishes directly to HTML, so you can post your work nearly anywhere. Anything you create with it is completely free to use any way you like, including for commercial purposes.
CryTek’s CryEngine includes TrackView, a non-linear animation timeline.