Find yourself bored with those simple old black headphones? If you want to spice them up, Adafruit's put together a guide to add Bluetooth controlled animated lights. The project runs through a lot of different skills, including soldering in the coloured rings, working with switches and assembling some 3D-printed parts. It's pretty far from practical, but that doesn't mean you don't walk away with practical skills when you're finished up. Plus, the end result has a decidedly Jet Set Radio vibe to it, which certainly isn't a bad thing.
Bluetooth Controlled NeoPixel Headphones [Adafruit]