All of these iPod nano case designs have three things in common. First, they cover all of the nano?s body, except for its screen and bottom, which are left open. Second, they all come in a black version, as well as at least one other color option. And third, each has at least one distinctive frill that may clinch its appeal to you, even if it doesn?t appeal as much to someone else. Several years ago, Power Support explained its case development?