Well the easiest is of course to just bring the laptop with you.
If the laptop is in a fixed location, there might be a way to wire external video through the walls although I suspect this will be complicated. I'm also guessing that this is not the way you want to go.
It might be easier to put a lower end computer by that screen and use it like a media center though.
There are a host of media players that might help as well.
Sonos (a bit pricey for this instance) would give you a wireless control you could carry around with you with a screen for the music. Very cool, but was too much for my taste (plus I wanted the control, not the wireless zones).
I was originally thinking an old audiotron (probably pretty cheap on ebay) as the laptop could bring up the songs, but you would only see what is playing in the living room on the 2 line display.
Not sure on the itunes hookup but dlink made one that I think got some decent ratings. It would get your songs from across the network (possibly a problem depending on how you are setup with drm) and display it on the screen. I think they went for a few hundred.
There may be a wireless pc transmission signal device, but without another pc on the other end (an rdp connection might satisfy your needs, although not the cleanest).
You could always of course setup a cqc or mainlobby server again connecting it to your tv (tying back to the media center concept). IVB's posts with the cheap touchpads might solve more than one of your problems. A very cool solution indeed, but possibly more involved than you were thinking.
You didn't put a budget on it either, but this might give you some ideas to think over.
