My first day at CES my battery ran out of power mid afternoon. Thankfully, I had my charger with me, but I had to awkwardly stand at a hallway outlet for 15-20 minutes while my phone charged. So I went in search of a cool battery/ case combo. I came across Third Rail's Slim Case with Removable Smart Battery and have been using it ever since. It works really well and it is not at all bulky. I like the sleek design and feel of the case. The battery is removable which is a big plus -- you don't have to attach it until you need it! Even when attached, the battery doesn't add too much bulk (it weighs 1.4 oz). As a bonus, you can also connect other devices to the battery pack (which has a universal charger) to charge them as well. Specs on the battery: 1250 mAh Li-Poly. The case retails for $89.99.