Developing an iPod armband is fairly straightforward: cover as much of the iPod as is possible with a case, provide a neoprene or elastic band to hold it on your arm, and price it reasonably. Marware has been doing this for years with various, iteratively improving editions of its Sportsuit Convertible cases, each well-designed and popular with iPod users. Now the company has released separate Sportsuit Convertibles for the iPhone and iPod touch ($35 each), built upon the same general components, but with interesting differences in their approaches to iPod touch and iPhone case design.