Boing Boing points to the dancing almond optical illusion which I had seen before and refers secondarily to the checker shadow illusion which is actually a lot more interesting. You definitely need to check it out – your brain will fight your eyes. At first you’ll absolutely refuse to beleive that the squares are the same color. I validated the accurracy of the illusion with photoshop’s eye dropper tool and it’s 100% legit. Amazing.
Bonus Emo Phillips joke: I used to think the brain was the most fascination part of the human body… then I realized, well look who’s telling me that.