I made this app, which takes a screenshot of the nook every 1:50 minutes and saves it to /media/screensavers/ScreenshotSaver.
When the nook goes to sleep after 2 minutes of inactivity, instead of showing a useless screensaver, keep showing whatever it was doing so I could keep reading my book/grocery list/map/whatever, without waking up the nook. Thus saving both battery and annoyance.
the app launcher simply toggles screenshots taking on and off. State is maintained between reboots.
On the first run it also creates the folder /media/screensavers/ScreenshotSaver, so after the first run you should go and change your screensaver to ScreenshotSaver.
I hope someone would find this thing useful.
source can be found here (github).
download app from attachment.