Add support for Subsonic as a music source
Subsonic is a popular self-hosted streaming server. Large libraries do not fit on most mobile devices (I have over 2TB of music).
There are over 40 apps that support Subsonic and the API is readily available.
CrowdPlayer is the best app I've seen for a jukebox server. Adding support for Subsonic can provide the backend for people who have a lot of music.