I'd get one of these or a device like it that can be oriented to an A4-ish size. I'd just run a full-screen emacs session in it (and subsequently would be forced to figure out how to highlight code with such a limited palette). I really enjoy E-Ink displays for reading for any amount of time over LCDs; even high-density panels (though they make it easier to read for longer periods than their predecessors, E-Ink still wins due to limited color range and not being back-lit by a thousand tiny suns).

Can't wait to see more of these on the market!