We have covered various smart rings in the past. The RUI Smart Ring happens to be one of the most fascinating ones around. RUI integrates remote control, gesture control, multi-touch control, augmented and virtual reality control into one. It can replace a remote, mouse, keyboard, trackpad, and an augmented reality controller. It has sensors (accelerometer/gyroscope) and a multi-touch surface and can be worn on any finger. You can use it to control multiple devices.
RUI supports hand and finger gestures and gesture combinations. It can be paired with augmented reality glasses to help you get things done easier. You can also use it for gaming (iOS/Android/Windows gaming). The device is expected to have an open SDK. It is on Indiegogo.