This is a fun optical illusion that I saw here and decided to recreate.

Stare at the black dot near the center of the image for 30 seconds. Then mouse over the image without moving your eyes. The image will become black-and-white, but it should appear in color (the flower is a red poppy) until you move your eyes.

Color illusion (must load images)

Original photo, which I shot somewhere in Israel.

Update: that was fun. I made a second one.

Color illusion #2 (must load images)