This will eventually be mounted on the center console of my car and hooked into the PC to control music and GPS navigation. Hardware wise, it's a Teensy 2.0 microcontroller hooked up to a few buttons purchased from Aliexpress in a plastic project box.

On the PC side, I have the physical media controls and knobs translated into commands using AutoHotkey so I can change what they do based on the open application. For example, in Winamp, I'll have the scroll knob press the up and down arrows. In a web browser (Which I use for Google Play Music), a mouse scroll wheel is emulated.