Let's first see what we need for this project. Apart from the usual Arduino Uno board, you will need XBee modules, both for Arduino and your computer. Here is the Arduino board with an XBee shield mounted on it, along with one XBee module:

As your computer doesn't come with built-in XBee, you will also need a module on your computer to communicate with the Arduino project via XBee. To do so, I used an USB XBee explorer module from SparkFun, along with an XBee module mounted on it:

To control an electrical device remotely, you will also need a relay module. For this module, I simply used a 5V relay module from Pololu:

For the current sensor, I used a board from ITead Studios, based on the ACS712 chip. Of course, you can use any board based on this chip.

To actually connect an electrical device (I used a 30W desk lamp for this project) to your project, you will need some power cables. You will need two of them: one male power plug that you will use to connect...