The UnSuggester. It isn't new, but a few months ago, I stumbled across this entertaining feature at LibraryThing, a website where people can list the books they've read and connect with other readers. The UnSuggester is a search engine where you enter a book, theoretically one that you own or have read, and are given a list of books that are least likely to be right for you.

The results are based on which books are missing from the collections of LibraryThing users who have the book you give. It doesn't always seem to work, and I'm not sure how scientific it is, but it makes for a fun game, seeing which book tops the list of "unsuggestions" for a particular title. Here are some of the better pairs that I found:

My Life by Bill Clinton ≠Don't Waste Your Life by John Piper

Your Best Life Now by Joel Osteen ≠Dune by Frank Herbert

Orthodoxy by G.K. Chesterton ≠Shopaholic Takes Manhattan by Sophie Kinsella

Paradise Lost by John Milton ≠Mason-Dixon Knitting: The Curious Knitters' Guide ...