This is interesting... Amazon has this new feature:
*Concordance*
Concordance is an alphabetized list of the most frequently occurring words
in a book, excluding common words such as "of" and "it." The font size of a
word is proportional to the number of times it occurs in the book. Hover
your mouse over a word to see how many times it occurs, or click on a word
to see a list of book excerpts containing that word.
I discovered it when I moused over the front cover image on the book page.