Allright... So I just ordered one off of Digi-Key (along with a CardKB keyboard for its first accessory). I can't wait to start working on software for it - I'm rusty as hell in C, but have been long itching to re-acquaint myself with it anyway (I live in Python these days).
For a reader, I can at least get a head-start now because I plan to convert ePub/Mobi to a 'native' markdown with tags for inline images and possibly internal hyperlinks. That way images can be resized approprely and converted to 4bpp greyscale on my computer and the text otherwise optimized for this particular screen.
Second use will be for sheet music - Being able to put a full lead-sheet with treble staff and chord symbols on the screen would be great. That too I can get a head-start on - some Python and Lilypond and I should be able to generate nice 960x540 sheet music pages in lovely black and white. Now there's some neat possibilities there - I just started playing saxophone, an instrument like many others with a standard attachment point for a music holder for use in marching band and etc... I'd never imagined actually using that holder, but this device is just about the perfect size. With a button (or few) added (perhaps attached to the bell of the sax where they can be easily reached) that could be *VERY* useful - the simplest case just being a next-page button to compensate for the tiiiinny screen and the limitations thereof, but more interesting might be adding a visual metronome and score animation (highlighting and counting off the beats in the current bar, basically) that could auto-scroll... and it would even be possible, with a second device as a midi-synthesizer, for it to act as a midi-player (able to transpose, adjust timing, etc.) while displaying the animated lead-sheet on screen.
Then it'll need a nice editor - that's part of why I ordered the CardKB with it which, while the tiny keyboard is probably not especially practical, it is good enough for prototyping, compact, and absurdly cheap. Paired with a nice PS/2 keyboard, though (like this one:
https://www.adafruit.com/product/857 ), this little screen could make for a very nice distraction-free writing environment. So it needs a nice little markdown/text-editor that can both offer an on-screen keyboard as needed, and ditch it for full-screen editing with a physical keyboard attached.
FINALLY, a hackable usable piece of e-ink hardware! I've been looking at Waveshare screens for a couple years and keep thinking about building a device around one - probably would have by now if any were touchscreen. But this thing - about the same price as Wavshare's slightly larger but lower resolution displays, with a case, battery, microcontroller, and three physical buttons... Hell Yea.