As many others have mentioned, this is a well-explored field. Golan Levin maintains a very extensive list of slit-scan camera experiments, check it out for some awesome examples: http://www.flong.com/texts/lists/slit_scan/
This pic [1] always used to bug me. Finally makes sense. [1]: http://www.flong.com/storage/images/texts/slit_scan/lartigue...
This was made on a large format camera -- probably something like 4 x 5 inches -- with a focal plane shutter. The shutter has a huge distance to cover -- 4 inches -- and it takes a while for the slit to cross the whole film frame.
The camera panning on one direction caused the spectators in the background to be distorted in one direction, while the car was moving faster than the camera and is distorted in the other direction.
Its interesting to note that the distortion was mimicked in cartoons as a way to show speed.