Around these parts, we like our gadgets. Unfortunately, accumulating a couple of them leaves us regularly in need of juice. Power outlets become scarce after stepping outside the house, which is why it's worth picking up an external battery pack or two. Currently you can get an Anker Astro E5 15,000mAh battery pack for $49.99 from Amazon, but with a coupon code, you can bring that down to $35.99.
This external battery comes with two USB ports (5V/2A and 5V/1A), so you can charge two devices at once.