Every so often you might come across an app you need from the App Store where the developer hasn’t even bothered to update the interface for the latest iPhone resolutions. In most cases, this means they’re still designed to work on the iPhone 4s resolution or earlier, and this leaves unsightly black bars at the top and bottom of the app.
As frustrating as this is, Apple still allows the apps to run (not for much longer), but they just won’t look as nice. A new free jailbreak tweak called PerfectFit by Tony Kraft can force these apps to run at a much more native-feeling resolution so they look better too.