I’ve covered this in past posts:
With so many people buying an eInk device — Nook Touch — for the first time, I thought I’d do it again.
There’s also a Barnes & Noble forum thread tutorial here: Wallpaper/Screensaver Tutorial. It mainly covers the classic Nook, though.
The image at the top of this post came from BooksForNooks: Wallpapers / Screensavers.
At Kindle and Nook Dragon Screensaver you can find stunners like this one:
The Nook Screensavers blog hasn’t been updated since last year, has only a few, but a great one like this:
Nook-Look is dedicated to screensavers. But beware: Not all are pre-scaled to 600×800. Some are very small, like this:
When enlarged and converted to grayscale, it becomes this:
This blog post has a few, including this one I love:
A public library (scroll down there) offers four screensavers, including this one for you print fetishists:
Finally, from Deviant Art comes this one: