Digital Lifestyle Outfitters has released a new line of Shell cases for the second-generation iPod nano. Each matches one of the colors of Nano available and is made of polycarbonate thin enough that it is not much thicker than a skin. The Shells also come with two interchangeable backs: a translucent one for fitting in pockets, and a more solid opaque one with a belt clip. Jacks and controls remain exposed while the screen is protected with a transparent layer. Each Shell costs for $20.