One of the most consistent complaints against phones of all types, including Android superphones favored by most of our readers, is that they have to make due with tiny, weak speakers. That's not anyone's fault, really - devices that fit in your pocket with enough technology to make Ray Kurzweil drool have to make some sacrifices. But  to rectify this situation, especially when you're traveling or trying to share music with lots of people, an external speaker of some kind is almost a necessity. Enter Logitech's Z515, a portable battery-powered Bluetooth speaker that intends to bring big sound in a small and easy-to-move package.