Use your Arduino with a suitable transmitter to operate remote radio controlled devices. This method should work with most popular low-cost power outlet sockets and light switches with 315/433mHz support.
All you need is an Arduino, ESP8266, etc, a 315/433MHz transmitter. And your existing remote control devices with a SC5262 / SC5272, HX2262 / HX2272, PT2262 / PT2272, EV1527, RT1527, FP1527 or HS1527 chipset. Also supports Intertechno outlets.
(Initial testing works great but further testing is needed)