I need a cheap, tiny, digital camera with zoom and adjustable shutter settings. What's the best one?

I need this for a very specific and unusual purpose. It has to be small enough to tape to the eye piece of an otoscope or microscope. A regular digital camera is too bulky and heavy. I need something about as big as a credit card. It has to focus at only 10 inches. It can shoot still shots or video, but I must be able to adjust the aperture and shutter speed to take a shot with fairly low light and no flash. It doesn't have to be super high resolution, but it should be reasonable. Anyone have experience with some very small digital cameras? Give me some brand names and models.