An eInk-like display that is truly bistable (a static image remains when power is removed), and has modes for partial refresh without corrupting adjacent parts of the screen, and for higher speed updates adequate for video.
Technology Review: Cheap E-Paper Displays Coming to a Store Near You
The demonstration unit looks like it may be only two-color (black/white), but the
Nemoptic web site indicates there are prototype versions in greyscale, and color (which may not have the same capabilities as shown in this demonstration.)