An audio player app to unite all the disparate music streaming services into a cohesive web application. It will be able to play web-hosted mp3s, YouTube, Soundcloud, Spotify, Last.fm, etc. It will let you create playlists with songs from any service simultaneously, so you can get all the songs you want in one place. You can follow other users' playlists too. One must already exist, but it appears the ones that have have been shuttered.