Have you ever forgotten to turn off your electronics before going to bed or leaving your home? A smart power outlet could help you with that. You could always buy one or build one on your own. deba168 has shared a guide that shows how you can build a smart power outlet with an Arduino Nano, Bluetooth, LM35 temperature sensor, plastic enclosure, and a few other parts.
The Smart Power Outlet lets you turn on/off your lights, control RGB LED strips, and even gather sensor data. More information is available on Instructables.com.