So one of the great things about the Kindle is that Amazon can see what books and how often passages are "highlighted". Some might be put off by the "big brother" aspect of this, but I think it is fascinating.
In case you are interested here is the most highlighted passages of all time and the most highlighted books of all time.
And for you Bible junkies, here are the popular highlights in the Bible.
I am sure it goes without saying, but this is only those that have been highlighted on the Kindle.