The ESP8266 and ESP32 have opened up a whole new world of diy projects that involve connecting to your network. These modules are tiny and will allow you to do simple things like control a light or keep tract of the temperature and service up a web page so you can view the current temperature and humidity.
I have created a couple of different projects that control my landscape lighting. I have a board that controls a single light and another that controls multiple lights. There are both 12v and mains versions. This is all based on an Arduino library created by Xose Pérez . The original library emulated the WeMo switch but has since been updated to emulate the Philips Hue light bulb which allows for controlling the brightness.