Ever have a View-Master as a kid? I think that was my all-time favorite toy. I absolutely loved the 3D images of cartoon characters, travel spots, and famous people. I could spend hours staring at these, sometimes closing one eye so I could again be bowled over by the effect when I re-opened it.
Numbskull that I was, though, it never occurred to me to try taking stereo pictures myself. I understood the whole concept ... take two pictures from about 2 1/2 inches apart, and find a way to view them so your right eye only sees the right image, and your left eye the left one. Since this is how we see things normally, the brain interprets the slight differences between the right and left images as depth.
About a dozen years ago, I discovered that not only are there are people who take their own stereo pictures, but there are special cameras and other equipment for taking and viewing them. Alot of this stuff, film equipment from the 1940's to the 1960's, can be found on eBay for pretty reasonable prices. Of course, these are not state-of-the-art automatic cameras, so it takes a little learning to figure out how to load film, set exposure, focus and shoot. You also have to learn what to do with the film once you've shot it. If it's slides, you have to have the film developed, and learn how to cut and mount it yourself. For prints, you'll have to find a place that can do custom cutting.
The simplest approach is to use two cameras, either film or digital. Put them side-by-side, so the lenses are parallel, and get them to shoot at the same time as best you can. If you use digital cameras, there's software that can display the images on the screen in a variety of formats, including those cheapie red/blue glasses you get a movie theaters. StereoPhoto-Maker is one such free package.
For still subjects, you can even use one camera. Shift your weight to your left foot and take a picture. Then shift your weight to your right foot, holding the camera steady so it basically slides to the right, and take another picture. This is the cha-cha method.
This can be really fun! A little Google searching will turn up a number of Web sites on Stereo Photography, its history, techniques, cameras, etc.