For self hosted music lovers, I would like to introduce you to Tempo, an open source and lightweight music client for Subsonic, designed and built natively for Android.
I'm waiting for more comprehensive offline support, but it does look promising. DSub and Ultrasonic are other good FOSS subsonic clients (although DSub isn't being actively developed).
EDIT: Actually looks like there has been some recent activity with DSub, which is great to see.