Positioning the flash about 2" - 4" above the lens will reduce red-eye but also drop the shadows created by the flash behind the person. You won't see a dark shadow if you photograph someone close to a wall if the flash is in that position. There will be a huge shadow if the flash is level with the camera and a few inches to one side! I've seen these attachments before but never figured out why anyone would want one.

I use a Stroboframe Camera Flip, the bracket is held in the same spot with your left hand and the flash doesn't move (always on top). Your right hand works the camera, and it has a mechanical linkage so the camera can be turned 90 degrees while attached to the bracket. Hard to explain but it works well. Actually it doesn't fit on one of my cameras like I found out yesterday... A friend uses the Flash Flip where the flash moves, not the camera (in relation to the bracket). Both are fine, but get the anti-twist plates too for both the camera and flash.