If you want to dabble in 3D on your SLR without having to use separate frames or “gluing” your cameras together, this 3D lens accessory by Loreo might be a happy solution. The Loreo 3D Lens-in-a-Cap is a standalone lens that mounts onto the camera body like a normal lens. The resulting image is duplicated side-by-side, and can be enjoyed in 3D with a special monitor viewer.
You can see sample photos taken with the accessory on the Loreo site.
The Lens-in-a-Cap is available for Nikon, Canon, Pentax, and Sony/Minolta mounts for $150. Individual monitor viewers are $2.50 or less.