1.

a. Hold the picture 1 close to your face so that your nose touches it (You might want to print it out.. you know its the flu season :P)
b. Slowly move away from it and try not to focus on 1
c. Continue moving it away from you very slowly until you see a Shark.

Now for the question. What are images like 1 called?

Cracked by: udupendra, deepak, teju, sidsen, jayanth, shivathilak, Abhishek, iamniks, Gammafunction, asha, Anonymous, alephnull, Tathagata Chatterjee, Biki, Madan, Mahesh, nisha’s thambi, bobo, prasanth, and Poornima (list was wrong. Fixed on 25/11/07)

Answer: Autostereograms.

Almost everyone cracked it, but not everyone could see it :-)

(I’m one of those who couldn’t see it either… Anyone know why some of us can’t see it? -Srikanth)