(via Bad Astronomy)

I love MagicEyes, where you diverge your eyes to see a 3d image appear in a staticky picture. The technical name for them is a 3d anaglyph or stereogram. I’ve gotten so good at them that I can diverge my eyes at will without straining. Well now it seems that someone has put together an animated one! Check it out.

Animated anaglyph gif

By the way, it’s been around for a while now, as its already on the wikipedia page about Stereoscopy. Can’t figure out what it is? Hover your mouse here.
UPDATE: Apparently, the host doesn’t like hotlinking - linking directly to their animated gif, even though I linked to their site as well, so at first the image didn’t show here. All fixity now.