The original Nook e-reader demonstrated that a small secondary touch-sensitive LCD display panel could be helpful for navigation and other tasks on the e-ink device. In an interesting symmetry, Microsoft Applied Sciences Group has prototyped a keyboard cover with a secondary e-ink display built in, to be used with its Surface LCD tablet. Inspired by the Microsoft Adaptive Keyboard, this prototype extends the keyboard’s input capability by providing a programmable multi-touch surface which can change its contents depending on the program in use. They chose to use e-ink for the display because of its extremely low energy requirements.
The demonstration video shows the 1280 x 305 screen being used for tool palettes in programs like Photoshop, or for reading or sending e-mail while in a video conference on the main screen. It can be used for repositioning maps or graphics on the screen using multitouch, or taking handwriting input, while keeping the user’s hands comfortably horizontal. Another possibility is browsing through images then selecting one to add to an e-mail.
While the video doesn’t show any uses specific to e-reading, I could imagine it being useful for e-books, too. What if touching a footnote link would pull up the footnote in the secondary display so you could read it there without losing your place in the main screen? Or if you had to look up the definition of a word, or even follow a web link, it could pop up a browser. You could even switch the places if you wanted to view the web page on the bigger display while keeping the book open in the smaller screen. Those are just my ideas, and I’m sure there are plenty of other ways that it could be useful.