Check this out
Pink Dot

Very cool...

I experienced all three situations...pink rotating dot...green dot and green dot with no pink dots...

Interesting...!

WhatFurrer

So much for trusting your senses.

Here's another cool one. If you squint your eyes really hard or back away from your monitor, the images should appear to switch places (i.e. the frowning man will be on the right and the woman on the left).

That one isn't doing anything for me. I guess my eyes work too well?

The pink dots are very cool though.

I don't "see" Peter's example, but I like how quickly effective the pink dot thing is.

I believe the cones in your eyes burn-out and recharge fairly quickly; the green/pink illusion is the most common one.

Both really cool.

Oh THAT is weird, Peter. How the heck does that happen?

Here are three illusions that should work for everybody. These images are NOT animated, but that doesn't keep them from moving. (If you want to prove it to yourself, stare at one spot for a while.)

Whoa, those are creepy!

Try scrolling over them. It's even weirder, especially that last one.

Makes me feel drunk.

I wonder how Spiff sees these?

The third makes me crave almonds....

I was thinking football, but now that you mention it, almonds look just about right.