Nathan Torkington at the new O'Reilly Radar blog points to a new feature on Amazon that can show you the most frequently used words from and various statistics on many books.
For example, here's the concordance and text statistics for Applied Cryptography.
This is cute, but not very useful. I'm not sure I care that Applied Cryptography averages 1.7 syllables per word or that the most common word in the book is "key".
The "books on related topics" on the same page might be more useful. Amazon says the relationships are determined using their new SIPs data. It would be fun to experiment with using this text analysis data to try to find improvements to the accuracy of Amazon's personalization and recommendations.