Phone-O-Scope: Closeup image comparison
The slightly odd Phone-O-Scope, which is an adapter to affix SLR lenses to iPhones.
Build instructions and more details are here.
Comparing iPhone to Phone-O-Scope images - iPhone on left, Phone-O-Scope on right. The Phone-O-Scope isn't quite as sharp, but you can clearly see how the camera now has a definite DOF effect - in the standard iPhone picture, nearly everything is in focus. Taken with the 50mm lens.