FabianK, thanks for the reply. That head unit was exactly what I'm after but I've found a cheaper way to do this, actually only cost me $3.
A few years back I installed an Alpine 2 channel amp and pioneer 6x9 3 ways in the rear parcel shelf to go with my Sony CD deck. Now, I don't listen to the radio at all and my CD collection is now on my ipod. So I just disconnected the RCAs from the Sony Head and plugged in a 3.5mm -> RCA cable from my ipod to the Apline Amp itself. voila. Works a charm and sounds fantastic and using the volume control on the ipod is just a joy.
It's got 6GB of music on there already and 24GB free. At almost 1500 songs I would have to drive for 8 days straight to listen to them all.
Now my next project is to build a nice little bracket mount to dock the ipod in while driving. too easy.
Thanks again for the replies.