ESP8266 is very interesting piece of electronics since it is very small, affordable (some 4 USD) and powerful since it has WiFi and can be used as Arduino.
With this project you can control your electric devices via WiFi remotely and setup a simple DIY smart home project for a fraction of a price of commercial proprietary solutions.
Sockets are fully 3D printable and are of standard European "Schuko" type, designed in Autodesk Fusion 360. Design is modular so you could probably easily change it to any other socket standard.
There is even an iOS app for remote control of modules. Project is also open source so they get extra pints in my book.
Project homepage with all the code and instructions:
GitHub repository with all the code and STLs:
Stay safe when working with home electric power systems :-)
looks like there is a simillar commercial system that is also very affordable, but it is not open sourced:
It may be possible to flash it with custom firmware but it doesn't have a socket but the wires should be connected to it.