Sony makes a racquet at CES 

Don’t get too excited, tennis fans. Sony’s Tennis Sensor is only a prototype. But, still, it could be worth waiting for. The sensor attaches to the base of your racquet, as you can see, and then detects the racquet’s movement through the air, as well as any vibrations when the racquet hits a ball. It then sends that data over Bluetooth to your phone, which has an app that tells you what it thinks of your swing: whether you’ve got enough back swing, whether you’re swinging too much like a squash player, whether you’re hitting in the ball in the sweetspot, that sort of stuff.