"I don't know why anyone would have a proprietary "marine" display aboard a boat "
Truly daylight-readable screens are damned expensive. Add a waterproof seal around them, and doubly-damned expensive. (You can blow out a conventional laptop screen just be spraying cleaner on it and letting it dribble into the bottom edge.)
I suppose you could put a conventional flat screen on the binnacle and then shroud it like an early radar display, stick your face in the hole to read it. But I'm impressed with the new Palm Treo's. 320x320 screen is almost 1/2 VGA, fairly crisp and bright, bluetooth, and not ultra-expensive. If there was a way to pull everything together belowdecks and then pipe it up to Treo's on deck via BlueTooth...that might be a nice multiple display system.