The best iPod form factor for the gym is the smallest - translation: the iPod shuffle. I first resisted the iPod mini but turned into an iPod mini convert after using it at the gym. Although the iPod shuffle desperately needs a display, at only 0.8 ounce, it is perfect for the gym. My favorite case for the iPod shuffle is the Action Jacket from DLO Direct, a cool neoprene case and armband combination. The included belt clip rotates 180 degrees and a clear vinyl screen protects the iPod controls from sweat. Pick up the DLO Action Jacket for US$24.95 from everythingiPod.com.