Belkin has introduced its new Headphone Adapter for the third-generation iPod shuffle. Allowing users to listen to music with any set of headphones or earphones they like, the Headphone Adapter is a short black cord with a headphone plug on one end and a female jack on the other, with an in-line control box in between. It lets users adjust volume, skip tracks, toggle between playlists, and hear a song title, using the same commands they would on Apple’s…