Seller Blue Neon Tavern has a lot of computers in his basement, some of which aren’t connected to his network. Rather than having to walk down there every time he’d like to turn a particular computer on or off, he came up with this clever little WiFi relay board.
The device uses an ESP8266 MCU for control, along with a relay that can be wired in to the motherboard on/off pins. It’s powered by a simple USB cable, and can be activated via a web server, or using ESPNOW as an alternate direct over-the-air control method. The board comes with a nice 3D-printed enclosure, along with 3 zip ties to secure it in place wherever it’s needed. While meant for computer control, it would seem like a great solution for activating a wide variety of devices that need a simple on/off signal.
One could see several of these devices distributed around the house/basement to keep all of your computers (or whatever else) under control. If you need more WiFi control options at a certain location, you might also check out this larger 4-relay ESP8266 module.