Time Machine
Suggestion: Play at Medium speed. You can zoom with the mouse wheel and pan by dragging with the mouse. See how sections of the image change over time. You can also drag the time slider to scrub back and forth in time.
This one is my first try, and needs refinement, but still is fun to play with and envision what a “real” one would do. This has only one Gigapan per hour, so the transitions are not real smooth.
See more information on Gigapan Time Machines.