First off, I apologize for making these images a few pixels over the limit. If I made them any smaller, there would be a significant loss of ability to see detail. Second, sorry if this has been done before or if there's an official thread for it.
Turn off any room lights that may cause a glare on your monitor
Sit at about arms length away from your monitor.
Center your nose on the seam between the two images
Slowly cross your eyes until the images overlap and "lock together"
If all goes well, you should see a 3D image in the middle, and 2 faint 2D images on either side.
(Note: If you have trouble, try moving back and forth, or adjusting how much your cross your eyes. You'll get better with practice)
(Dot added to make it easier to line up)
Hope you all enjoy. If I get a good response, I could always do some more, or give you instructions on how to make them yourself