As much as we?ve liked a number of PDO?s slightly-better-than-commodity-class cases for various iPods and the iPhone, the company?s new Flipp for iPod touch ($30) had us asking one question: what would it take to get companies to stop making me-too, flip-style iPod cases? The simple answer, of course, is ?if people stop buying them,? but it seems like this stale category of cases never ceases to lure companies to release?