For descriptions of many of the ways of viewing stereo images see the Wikipedia entry Stereoscopy.
Examples of many types of viewer used for technical purposes can be found at http://www.stereoscopic.org/index.html.
Start 3D have a very interesting website for sharing 3D photos.
If you've got a pair of ColorCode glasses - the amber/blue ones - as used for Chuck 3D this slideshow should give a decent 3D effect. The colours aren't as good as they should be.
Aerial photos online