Every year I declare that when the next iPhone comes out, I'm going to buy the biggest one they sell. Yet when the time comes, I end up buying the 16 GB model. Every single year.
Mophie has attempted to take the sting off of that buyer's remorse with the Mophie Space Pack. It's a new version of their very popular Juice Pack battery cases, but this one has internal storage that allows you to store pictures, videos, music, and other files without filling up your iPhone. These files are accessible via the Mophie Space app, which can be set to automatically back up your photos and videos from your iPhone, drag and drop files from your computer, or even shoot photos and videos from directly inside the app.
The Space Pack has a slightly larger battery than the standard Juice Pack, but it won't net you any extra life--that is simply to keep as a reserve so that you can continue to access your files even if you've depleted the Juice portion of your Space Pack.
Up until now, Mophie has offered 16 GB or 32 GB versions of the Space Pack, but they've announced a 64 GB version recently as well for $249. Not bad considering you'll be doubling your battery life, and potentially quadrupling your device storage.