You'd think the iPod alone would be enough to satisfy travelers with the shortest of attention spans. But, of course, it's not. That's why there's an endless procession of accessories on the market, each one offering a new feature or convenient little twist on the iPod's most basic function: entertaining you on the go. We sifted through piles of add-ons to come up with the five coolest iPod accessories that'll make your next trip--whether it's to the supermarket down the street or to an island in the South Pacific--your most entertaining journey yet.