Pitched specifically at iPad owners but also capable of being used with virtually any USB device -- actually, five of them at once -- dreamGEAR's i.Sound Portable Power Max 16,000 mAh Backup Battery ($130) is without question the highest-capacity battery accessory we've yet tested for Apple's digital media devices -- as well as the largest. The 16,000 mAh battery inside is capable of recharging, say, an iPod touch 10 times, or roughly twice refilling…
