In this project, the author will show you how he repurposed the useless buttons on the TV remote to control the LEDs behind his TV. You can also use this technique to control all sorts of things with a bit of code editing. He will also talk a bit about the theory of how an infrared transmitter and an infrared receiver communicates with each other.
Arduino IR library: click here
More project info on Instructables (parts list, schematic, Arduino code): click here