Hi,
I used to play with creating them myself actually when they first came out, had a bout three different programs for creating them. I ran across one that really impressed me (done at a University I think) it was an actual picture of a park bench in a park., but when you 'focused' as a stereogram on the bench was a man with his dog at his feet..I was totally awe struck. then I got into 3D stuff (with red and blue glasses)and found you could create them also using an image editing program and separating the channels then off-setting the red and blue channels a couple of pixels and reconstructing the image back to normal.
Just a note and some rambling info.
Jim