Here is an interesting visual illusion (via Spluch) …
People at Spluch say that you should move away from the screen to see the face better, but you can also try looking at the image while shaking the head left/right or squint the eyes. Of course you can also move away from the screen, squint the eyes, and shake your head left/right. (You can try few dancing moves while you are at it).
I guess this is a good example of how rod cells pick up more information than cone cells can?
A brood comb 