The Myo Armband is a pretty interesting wearable device. It reads the electrical activity of your muscles and the motion of your arm, allowing you to control your things using gestures. You can develop all kinds of solutions for it using open APIs and its free SDK. The below video shows how one can use a Myo Armband to lock a computer:
As you can see in the video, with Myo Lock, you just have to double tap and make a fist to lock your Windows computer. The good news is you can do a whole lot more with a Myo Armband.