I recomend this app because its just a simple hundred-something long list of things tht are handy to have, like making it say the percent of battery in the top right corner, how to change songs without leaving the lock screen, prevent it from switching to landscape when lying down, and so on. A lot of the tips dont apply to most people, but there are still alot that are helpful. I highly recomend this app
gccyfu7yl about Secrets for iPhone - Tips & Tricks, v4.5