Hundreds of thousands of smart phone apps are on the market—so many that the catchphrase “There’s an app for that!” has been coined. You can check your checking account balance, and if you have something to sell, you can list your item using your phone. But those tasks are normal. If you’ve really perused deep into the AppStore or Android Marketplace, you probably have discovered you can do more than you thought you could—or should—do on such a slick, small device. Here are five apps that you might not have known, but now that you do, you might wonder how you got along without them.