While browsing around on ebay for composite A/V to VGA converters to try my N900 on a PC monitor, I came across these dinky little jobs:
7" TFT displays
What are the chances of getting one to work with the N900?

There's even touch-screen versions, but I don't hold out much hope for one of those actually working.

With the TV-out lead it will display on any composite input.
So wih N900 and a a camera hooked up.
You can watch a movie and when the reverse wire is triggered the rear view camera comes on.
Couldn't see where the audio plugs in tho. Maybe break into the cars radio.

Thankees for the feedback, but I think you mis-understood my post.

What I'm after is connecting the N900 to a portable netbook size display for use while on long journeys. Something that would fit into a small bag or suitcase pocket.
Another idea that has come to mind is: As the video out jack can be inserted/removed without shutting down the N900 (Hot plugged), make a cradle behind or under the 7" display that the N900 sits in. When a call comes in it's just a case of pull out the phone, answer and when the call ends drop it back into the cradle and it's back on screen.