I tell ya....my buddy had the same problem. Got 2 screens, and didn't know what to do with one of em! SO...he came up with a crazy idea, how about attaching a camera to the bottom of his car, so he can watch the road and stuff while driving! what a dork...BUT THEN, he got 3 more cameras...(all from x-10)...and installed one by his rear-view-mirror on the passenger side, one in the front grill of his truck, and one underneath the back bumper of his truck so he can see what's behind him. I have no idea how the hell he got this to work, or how he switches between cameras...but it works. I'll have to get him to send me some pics so i can post them. its pretty neat.
He told me when he first set it all up that it looked like he was playing Grand Tourismo but in real life! (you know how u can switch veiws and ****)....its cool.