... are playing with the new LibraryThing toy, Unsuggester
Unsuggester takes "people who like this also like that" and turns it on its head. It analyzes the seven million books LibraryThing members have recorded as owned or read, and comes back with books least likely to share a library with the book you suggest.
But unlike them, I can't get any really funny results. Indeed, I can barely get different results from book to book. Every book I enter yields a whole string of Christian self-help books ['how to accept that Jesus died a purpose-driven death so you can lead a prayerful life'], plus sometimes Eragon and Confessions of a Shopaholic. The fun thing about the toy is the ability to say, "aha! I defy your automated predictability, because I read both X and Y!" But I failed to find anything like that; I really don't own all of the books that Unsuggester predicts I won't own...