Chances are, you have a data plan on your iPhone, and you might benefit from being able to keep track of the data that you're using. A lot of data plans are capped these days, but even those with unlimited data on some carriers have to be careful of how much data they're using, or they run the risk of getting throttled data speeds.
A popular data-tracking Notification Center widget called WeeTrackData
by iOS developer Albert Schulz has been re-released with iOS 7 support. The new version