Mophie's Space Pack may be the only case in the world that offers better protection, more battery life and additional storage all in to one neat package.
The Space Pack has a huge 1700mAh battery packed right into it, so this will double the battery life of an iPhone 5/5S. It gives the iPhone more storage too, there are 16GB ($150) and 32GB ($180) options which will double the amount of storage on the 16GB and 32GB models of the iPhone. You won't be able to use the extra storage for apps but it can be very handy for storing files, music, videos and pictures. It can even just be used as a flash drive to store files.
Packing additional storage into the case itself is the selling point here, as I haven't seen any other case do that. There will now inevitably be many manufacturers who follow suit and make similar products.