I noticed many head units on the market that support bluetooth. But every single one I ran into only did the phone call audio, not some sorta music playback.

My buddy told me about a Sony deck back in the day that did this, but can't seem to dig up any more info.

 

The Pioneer AVIC-D3 does, as well as many other modern higher-end units.

The thing you're looking for is the AD2P protocol, which is the ability for bluetooth to stream stereo music.

 

I have this deck in my truck, and I run Pandora from my phone thru its bluetooth connection. It even will jump to the next song in Pandora or the mp3 player with the buttons on the headunit. I think most bluetooth Pioneer decks have both phone and music abilities

 

The JVC KD-AR815 does both bluetooth phone and bluetooth audio. Its an awesome deck with other great features too and the price is pretty nice as well.