Looks cool, so I feel churlish complaining, but I'd prefer it if the speed was varied by changing the distance/rotation moved, rather than the time delay between frames. i.e. like true slow-motion from a high fps camera.<p><i>EDIT</i> unfortunately, the approach he used precludes this: <a href="http://www.animatedengines.com/howto.shtml" rel="nofollow">http://www.animatedengines.com/howto.shtml</a> I guess it illustrates how rare it is to combine domain expertise (like that guy has), with an unrelated expertise in animation. If you have both (or access to them), you can make difficult things much easier, and so create value.