I came across a technique for making 3D pictures without having a multi-lens camera. The person on whose site (I think it was Flickr) I found it, called it the 3D cha-cha. It is done by taking two pictures of the same scene; one picture shot using your left eye to compose the picture, then without moving too much, shoot the same picture looking through the viewfindwer with your right eye.
The 3D effect is achieved by combining the photos on the computer and then viewing cross eyed as is the case with these examples or making a print that can be used with a 3D viewer. Both photos are copyrighted by Richard Biemann 2011.
Click on the photos to get a larger view then cross your eyes.