A-Level is a virtual, digital level (or 'spirit level'). It uses the iPhone's motion detectors to determine whether the phone is flat. If not, a numerical readout tells you by how many degrees off you are (or, for old-school DIYers, the traditional bubble-in-liquid display, just like Dad used to use).
You can use it in landscape or portrait mode or laid flat on its back.
Just how accurate is this? I don't know -- I don't have an iPhone to test it out, and my apartment was built two years before the Titanic sunk, so I doubt that anything's still straight in it. The product blurb agrees: "This application is for recreational use only". A future update will allow calibration, which should help. Really, it's only a dollar, so what do you have to lose?
Talk about a neat trick to show your buddies. (Or joke -- you could try to place your new digital level on your closest buddy's head and make a crack about him, but good luck getting your precious iPhone back.)
What do you think, readers? Useful, or just flashy? And what other practical uses could an iPhone app address? Tell us in TalkBack. (Thanks to Wired for the heads up.)