The first image is the parallel version. Just stare at the middle of the two images and another image should appear in 3D.
The second image is the cross version. Just stare at the center of the image while crossing your eyes and another image should appear in 3D.
Parallel Vision Image Pair
©2008 Richard Murray
Cross Vision Image Pair
©2008 Richard Murray
These were created using J-P Metsavainio's Stero Pair Action for Photoshop which can be found here: Stero Pair Action