There are a lot of smartphone juice packs and similar accessories out there, but the Sanyo Eneloop Mobile Booster actually manages to to be a little different.
First off, it can charge up two devices at once thanks to dual USB output ports. The KBC-L2 Mobile Booster provides up to 5000mAh of power (or 1000mA when charging a tablet or e-book reader) after being charged using the included AC adapter or via USB when tethered to a computer. To get a full charge, it will take seven hours via AC and 14 hours via USB.
Given how many devices can be charged using this device, obviously the extra juice time is going to vary by gadget. However, the Mobile Booster can stand in an external battery for auxiliary power when the built-in battery of your device is depleted.
The Sanyo Mobile Booster is available now and is priced at $79.99.