Don't be a rectangle...

...Be a circle! Meet the RelaySquid. It's a circular PCB with four relays that each switch an extension cord on/off , all of which can be controlled by an I/O board like the Arduino.

Not to be confused with any other type of squid:

There's also a plug that goes into the wall to power each of these outlets, as well as pins that connect directly to the Arduino to control each of the relays, in addition to powering the circuit itself.

It's super easy to get up and running, even if you're new to the Arduino. The pins are arranged as follows:

Just plug G into the Power GND pin on the Arduino, and V into Power 5V on the Arduino, and then connect your Arduino pin to a relay pin. Once you start switching your pins on and off, you can hear the relays clicking!

Here's a quick video I made to demo the project. I'll post some code later today.