Ever wanted your own entrance music? Over on Redpepper, they came up with a system that uses a Raspberry Pi and Bluetooth to trigger a song when you walk into an area.
The system here uses a Raspberry Pi to power a stereo, then a Bluetooth iBeacon to track where your phone is. The music itself is powered by Spotify and an iOS app.
For whatever reason, they don't include the full bits of code you'll need, but conceptually you should be able to pull what you need to make your own from their guide.