In the modern world, your smartphone is essentially your passport to everything you do or need on the daily -- your alarm clock, your wallet, your map, and well... your phone. And for the average user, that is what they remain limited to. But these are highly capable and advanced devices with so many niche use cases that many of us may not even be aware of. What's an underutilized capability of the iPhone that you know of, that anyone can tap into -- hardware wise, software wise... whatever.