This was rolled out a few months ago, but I must have missed it. Amazon searches the text of some of the books it sells, analyzes it, and publishes various metrics. The last book I read was Neal Stephenson’s Cryptonomicon, so that will be the example.

• Statistically Improbable Phrases (SIPs):
  grand wazir, substitution alphabet, data haven, hive mind, dive plan
• Concordance
• Other text stats like:
  Words/Dollar: 50,204
  Syllables/Word: 1.5