Many of you will have seen this before, but I rather liked the “Unsuggestor”:http://www.librarything.com/unsuggester. It’s meant to be the opposite of the tool you see on Amazon and elsewhere that tells you which books are bought by people who bought a particular book. This tells you which pairs of books are _not_ jointly owned. By the Amazon logic, if you like one, you’ll hate the other.

They have a list of books that don’t go well together on the side of the page. The top one is Kant’s _Critique of Pure Reason_ and Sophie Kinsella’s _Confessions of a Shopaholic_. The third is Augustine’s _Confessions_ and Sherrilyn Kenyon’s _Night Pleasures_. Here are some other pairings.

Austin, _How to Do Things With Words_ – E. B. White, _Charlotte’s Web_
Descartes, _Meditations on First Philosophy_ – Janet Evanovich, _Two for the dough_
Ryle, _The Concept of Mind_ – David Sedaris, _Me Talk Pretty One Day_
Russell, _History of Western Philosophy_ – Emma McLaughlin, _The Nanny Diaries_

Feel free to add more in comments!