I have an idea.  I think that all books should have a link to a vocabulary test website. 

You take the test once before you read the book.  The words tested on include a lot of words that could be new in the book as determined by running the text of the book through a program that compares the words against a catalogue of the most commonly used english words.  

Then, after you have read the book and encountered the words in context, you could take the test again and compare your score.  
This score improvement could be tweeted out.  For example "I just increased my vocab test score %35 by reading The Shack by William P. Young."

This would help students, make books a little more viral, and increase peoples vocabulary!  You could even offer a coupon for a different book by the author or publisher upon successful completion of the test.