Sanwa iPhone Stereoscope
The Sanwa (Japan) 400-CAM021 Stereoscope turns your iPhone into sort of a 3D View Master, allowing you to watch YouTube stereoscopic movies and side-by-side stereoscopic pairs.
The 400-CAM021 turns the iPhone into a big-screen 3D TV as the image viewed through the device is the same you may enjoy on a 60 inches 3DTV screen seen from 10 feet away. However, the resolution is a tad lower than on TV as the iPhone 4's Retina display gives you only 480(W) by 640 (H) pixels per eye; the iPhone has to share its 960 pixels per horizontal line between both eyes.
The 400-CAM021 weigths 127 grams and measures 104 x 75 x 90 mm. It may be used with iPhone 4 and 4S. The price of the device is around 1,980 yens including tax (25 $ or 20€). The Sanwa stereoscope is also available on the Japanese Yahoo store. Expect the price to double is you ask for transcontinental shipping.
Visit the original Sanwa 400-CAM021 web page in Japanese for more information (use Google Translate ay your own risks if you are not fluent in Japanese).