If you use your computer for playing music, chances are at least once you've wished you had a remote control for it. Hacker Owen Trueblood wanted the same thing, so he hacked a TV remote to work with an infrared sensor attached to his computer.
Using an old TV remote, an ATtiny13 microcontroller, and an infrared receiver pulled out of an old VCR, he was able to set up the remote to control the computer's volume by hacking the IR sensor into a USB. Since most computers don't come with a remote, this is handy if you're using a computer specifically for music playing all day long. You can find the full guide, including the source code for the control app on the computer, over on Hackniac.