Via Paul Bausch is news of a feature in that runs analysis on books scanned into Amazon’s Search Inside index. From Amazon’s site:’s Statistically Improbable Phrases, or “SIPs”, show you the interesting, distinctive, or unlikely phrases that occur in the text of books in Search Inside the Book. Our computers scan the text of all books in the Search Inside program. If they find a phrase that occurs a large number of times in a particular book relative to how many times it occurs across all Search Inside books, that phrase is a SIP in that book.

Yet another tool to hook you back to the Amazon mothership. Here’s a list of books that list the improbable phrase, thumb tribes.