I've had this idea that if we could ever get e-ink displays to actually be paper like (i.e. in thickness, and bendability and hatever other features you attach to paper books) it be interesting for observant jews an people who just like books to be able to sell "placeholder" e-ink books. i.e. books filled with programmable eink pages that you can flip through like a regular book. One would download a book and program it, and then just read it like a traditional book, flipping pages as you go. once done, you download another book to it and all the pages get reprogrammed.