Transflective LCDs are another tech that didn't go anywhere. It lets you use LCDs outdoors by reflecting the natural light, which solves the problems of color and video. There were even models with solar cells embedded, so not only you get longer battery life but recharge in the sun.
I think that's what the Pebble Time watches used, a transflective Sharp Memory LCD (that Pebble calls "e-paper"). In direct sunlight, the screens are actually easier to read, and the colors are really vibrant. Indoors, it's a bit dim without using a backlight, though still better than a blank screen. It seems to be the key to the Pebble's 7 - 10 day battery life even with an always-on display.