All the photos on this page are free-viewing cross-eyed 3-D pairs, viewed by crossing your eyes and gradually bringing the separate images together to form a single 3D image in the middle, much like viewing the 'Magic Eye' images that were all the rage a few years ago.
A website that explains how to view the images can be found here:
There is also a thread in the Forum with a discussion of 3D images and how to view them, and where many 3D images are posted: http://www.panoramio.com/forum/viewtopic.php?t=1660
All of the 'Favorite Photographers' listed on this page are other pages with 3D images, and most of those users would be glad to help you view and create 3D stereo image pairs. Happy Viewing!
(You can also see my non-3D images on my regular pages: Panoramio users 286174 and 569964)