If you are wondering if your tennis racquet needs to be restrung and you have an iPhone, here's a solution. raquetTune is a downloadable app that allows you to check racquet string tension any time, anywhere. The app uses the sound of the racquet strings to analyze the frequency of the strings when hit with a pen or like object. The frequency is then converted to the tension of the stringbed. The accuracy is shown by an indicator light on the display and can be improved by repeating the "test" several times in a row.

You can also use it to test whether or not your tennis balls have lost their fizz.

To download the app, click the tenniszoo link.