In the past I purchased Mugen Power batteries for replacement or extended battery options for my devices. They recently sent along their Mugenizer N11 Qi Wireless Power Bank. I have used other portable battery solutions in the past, but they all required a cable connection to charge up your phone. The Mugenizer N11 lets you place your Qi-compatible smartphone down on the top to recharge your phone.
Wireless charging is still not widely available in phones, but Nokia has made it a priority on their Lumia devices and uses the Qi standard. The Nexus 5 also supports Qi wireless charging. You can find cases and back replacements for devices like the iPhone and Samsung Galaxy that add Qi functionality.
The Mugenizer N11 Qi Wireless Power Bank has a 4,800 mAh internal battery that you charge up via a microUSB port. They include a USB to microUSB cable and a USB A/C adapter to charge up the battery pack.