There are free Nook apps for Android, iOS and Windows 8. They have similar display options, and the Android and iOS apps work with their respective built in screen readers.
For book content, the apps for Android, iOS and Windows 8 have a choice of font size, font shape and colour theme.
One unusual - and welcome - option in the iOS app is the ability to create themes using the colours of your choice.
The big difference is when it comes to speech or braille access. On an iOS or Android device, the Nook app works with the built-in screen reader, offering the option to read at the level you choose, from one character at a time up to one chapter at a time.
Not only that, but when you install the app with a screen reader running, it offers a short accessibility tutorial while the device is syncing your library. The tutorial can be started at any time from the Settings menu while the screen reader is active. If you're lucky enough to own a Bluetooth Braille display, you can use this to read your books with, too.
We've recorded some videos demonstrating the accessibility features for readers with sight loss.