The Exovolt Plus battery is the world's first stackable battery. The main battery can hold a 5,200 mAH charge, a respectable size. On top of that, you can buy sub-batteries that stack on top of the main battery to increase the amount of power you have on hand. If you have unlimited sub-batteries and are good at building block towers, you can carry around limitless power.
The Exovolt Plus battery is compatible with iDevices, and it also has USB and micro-USB ports as well. This portable charging station would be great for traveling, camping or power outages. This product is not available quite yet, but it looks good and is a great idea, so tech enthusiasts will be excited for its eventual release.