Here is another, spinning silhouette dancer is a bistable illusion where you can see movement both clockwise and counterclockwise.
First look only at the dancing girl on the left for a few revolutions, then look at the center girl, she is turning to the right, now look at the girl on the right for a few seconds, then look at the girl in the center, now she is turning to the left, however the the girl in the center has been turning the same way all the time!