Stereoscopic images are a basic way to give you brain a perception of depth from a single 2-d photo. However, it’s usually pretty difficult to get working without super expensive cameras and setups.
Well, Mathieu Stern discovered a cheap adapter called a Stereax on eBay for only $30. With alittle modification to get the adapter to mount to a modern lens, he was able to make some pretty neat 3-D images with just his regular slr. Now, stereoscopic images are supposed to be best viewed with crossed eyes, but most people are bad at doing that, so the other way of using PhotoShop to make an animated gif works to. You get the depth perception there, and that’s usually good enough to get the idea.