Patchbay is a jQuery plugin which helps you construct audio players for a site or web app, which hook into a single "master" audio player. By pairing this with a tool for constructing single-page web apps like Angular or Ajaxify, you can make an audio player that keeps playing music even as the user browses the site. I developed a similar library for my side project Polymath, and now I've developed it into a library.
Still a work in progress.