My new favorite time-waster is the UnSuggester on Library Thing. Suggest a title and it will suggest some books you are sure not to like. Some examples:

Did you like The Critique of Pure Reason?

You will not like Confessions of a Shopaholic. (I did, in fact, like both.)

Did you like The Confessions of St. Augustine?
You will not like Night Pleasures.

Did you like ANSI Common LISP?
You will not like Wuthering Heights.

Did you like The Road to Serfdom?
You will not like The Devil Wears Prada.

Did you like Bitch?
You will not like The Visual Display of Quantitative Information.

Did you like Real Sex?
You will not like The Unbearable Lightness of Being.