If you've got the money, buying two identical cameras will yield better
results that a stereo adaptor. I bought two Fuji F440s as they were
cheap enough, square at the back and had a tripod mount. Because of
their wide-angle lenses, the 65mm lens separation is unnecessary and
you'll get better stereo with a wider separation. Both cameras are
screwed to a simple L-shaped piece of aluminium (aluminum to the folks
across the pond) with a slot to allow the cameras to be separated
between 70mm and 150mm. I usually print two stereo pairs on an A4 sheet
in landscape. Reversing them for cross-eyed viewing - more detail! As
the cameras don't sit exactly square on the bar, I usually have to
adjust up or down the two images, but the Photoshop guides help line up
the two pix.

You could try this on stationary subjects using a single camera.

Take a look at http://home.att.net/~drt-3d/toys/realist/index.htm if you
ever feel like buying a film based stereo camera - I have one of these
Stereo Realists but seldom use it these days.