A smartphone can do many things, but you probably didn't know it could measure distance, height, angles, direction and sound too. The jack-of-all-trades Smart Tools is a $2.50 toolkit for the handyman in all of us. Its 15 measurement tools are divided into 5 sets. Smart Ruler Pro, for instance, is handy for measuring the length of objects placed on a mobile device's screen. Smart Tools also includes a protractor that works with the phone's camera, as well as myriad other tools. Professional measuring tools may be more precise, of course, but Smart Tools does well in a pinch. Besides, it's easier to carry than a real toolkit.