Squatting is the anatomically correct position for a bowel movement; it straightens out the kink in the colon and makes the whole process more efficient. It's also supposed to be better for bowel health -- leads to less straining and fewer hemorrhoids and such.

To that end, there are several companies out there that sell stepstools designed to allow squatting with western toilets. The first one I saw was the Lilipad, made in New Zealand, and more recently a company called Squatty Potty has started making them in the US.