Though we've almost had our fill of iPhone 4 cases at this point, Proof Cases has delivered something just a little different with Duo ($30). This hard plastic case is, like so many others, finished with a soft touch rubber in your choice of two colors: opaque black or translucent "smoke" gray. It omits button protection of any sort, leaving holes for not only the rear camera, top and bottom ports, and microphone, but also the ringer switch and side…
