Something like this:

Here

Of course it's not available yet and is specifically designed for the Dension player or an IPOD. I'm using a stripped down car computer and empegface to send to my Kenwood video screen. I control the trunk-mounted empeg with a SWI-X. Seems to work pretty good. The only change I'll probably make is to downgrade to 2 final (Too many glitches in 3beta)