Notion Ink Adam Tablet [1] Pixel Qi Display [2]
Altogether not a truly great tablet, but I loved the idea of the Pixel Qi display. Normal colored LCD when being used indoors with backlight enabled. But outdoors in the bright sun, the colors faded away and it became some e-paper like reflective display. That way you could use it for watching movies in the dark and reading books on the beach ;-)
Sadly the tablet had a lot of other flaws and the colors of the LCD weren't as good as the AMOLEDs we are used to today, but every time I see one of those ebook readers with b/w display I wonder why the Pixel Qi displays didn't make it.