While the iPhone takes great pictures, there are occasions when a better lens would come in handy. This is not the first lens available for the iPhone. There have been case mods that require taking apart your iPhone. There have been cases that have built-in lenses. This lens uses magnetic mounts, for easily changing them or removing them. There are also three different lenses to choose from.
Just attach a detachable, self-adhesive ring to the area around the camera lens. Then just attache any of the three different lenses to the iPhone. There is a wide angle, a telephoto and a fish-eye lens. Available lenses are a 2x Telephoto, a 170° FishEye (0.28X) and a Wide Angle 0.67X + Super Macro lens.
[$16.99 each from USB Fever]