People use e-readers to hide what they are reading...

Here's an interesting advantage of using a digital e-reader: you can read books you are are ashamed of... In a recent UK study it was found that 58% of e-reader owners use the e-reader to hide what they're reading. About one third of the users read erotic novels on their e-reader. People are also reading children titles (such as Harry Potter) - and the e-reader helps them do that in secret...

source: The Daily Mail