Any subject for which two views are available, a few degrees apart, can produce a good stereo pair. This includes, less obviously, subjects that are very far away, such as mountains, and even celestial bodies, such as comets, the Sun, Jupiter, and the Moon. If you fly often, I recommend a window seat in front of the wing on the shady side, with a few seconds between exposures.

A few photos are credited to others: the aerial view of Mt. St. Helens and San Francisco are by Adriana Huyer, and the solar images are from SDAC at NASA.

Try searching “stereo photography” or check out a very good site of photos and technical advice:
http://www.crystalcanyons.net/Crystal.shtm
or one of several vendors of useful equipment and advice:
http://www.berezin.com/3d/

Stereoposis
Stereopsis is the extraction of relative distance information within a viewed scene by the difference between two images collected from different viewpoints. Animals with binocular vision, such as humans, subconsciously construct three-dimensional representations of observed scenes using stereopsis. While there are a variety of visual cues that assist in the determination of distance (apparent size of known subjects, focus of eyes, convergence of eyes, decreased resolution due to haze), stereopsis is unbiased and accurate.

Despite the use of depth perception based on stereopsis in daily activities, especially hand-eye coordination (threading a needle, grabbing a handle), it was only recognized scientifically in the early 19th century (Charles Wheatstone, 1938).

Public interest has bloomed in various eras, and very soon after the invention of photography, stereo cameras and viewers became popular.

It has been the primary method of constructing topological maps, and there is current interest in computerized methods to extract distance information from images. Militarily, it was exploited for artillery ranging (especially naval), and has advantages over split-image and superimposition methods. It has also been the subject of considerable scientific inquiry, as an example of complex post-retinal visual processing. Educationally, stereo images form a very simple and powerful method to represent three-dimensional structures in two dimensional formats, whether paper or computer monitor, and are commonly found in organic chemistry and biochemistry textbooks and structural biology journals.

An estimated 5-10% of public are unable to perceive depth by stereopsis, despite having two functional eyes, often the result of early childhood problems preventing fusion of binocular images during a critical developmental period.

The average separation between the eyes in adult humans is approximately 65 mm, and since discrepancy between two viewpoints differing in as little as 25 seconds of arc is a typical threshold, humans can perceive objects as far away as 500 m as being closer than infinity.

As an aspect of photography, stereo photography is sometimes regarded as a gimmick, but many enthusiasts will argue that it can be an excellent method to explore another dimension to composition.