Image Credit: Droste Effect: manyone1, Original: svacher
Flickr user Pisco Bandito wrote a tutorial on how to create your very own Droste effect [wiki] photo using Mathmap for Windows and GIMP.
Or you can just gawk at the cool photos others had created at the Escher's Droste Print Gallery [Flickr] - via Microsiervos (whom we always love!)
Previously on Neatorama: Droste Effect in Escher
The effect it simulates: http://www.subblue.com/blog/2008/11/17/eschers_droste_effect
Wish I had CS4!