My friend Eric (who seems to be MIA of late) sent me this information a while back. It's a host of optical illusions, which I really enjoy. I had only seen three or four of these, so it was quite the revelation.
I really liked this one. There is a human face somewhere in the mass of beans. The weird thing is that, once you see it, it's pretty much ALL you see.
I used to teach a high school course on World Cultures, and one of my opening activities was trying to explain ethnocentrism. One of the ways I did this was through optical illusions. I tried to get them to understand that the way YOU see things is not necessarily the way other people see things, or even the way they really are. Among a host of others, I used the classic old woman/young girl picture and let them try to prove their side before explaining the picture, and that both sides were right.