The worst inclusion is the one I read most recently: The Catcher in the Rye. The only reason I finally picked it up last year, to be honest, was that I felt a little like Mel Gibson's character in Conspiracy Theory: it was a classic that everyone had read, except me. I suppose I wanted to feel "normal".
Guess what? Normal sucks. Catcher is a lame excuse to force (or, alternately, allow) high-schoolers to read the F-bomb approximately one thousand times in one hundred pages.
So here are the other ones that I've read: The Bible (duh); Declaration of Independence/Constitution/Gettysburg); Huck Finn (though I preferred Tom Sawyer); Macbeth; The Iliad; Great Expectations; 1984; The Scarlet Letter; Chaucer's Canterbury Tales; Frost's poems; Dickinson's poems; and Machiavelli's Prince. Those are the ones I remember, anyway, and without exception I'd recommend them. I'm still partial to John Wesley's quote regarding The Prince (tip o' the cap to this blogger, who perhaps has been raised on the A Beka Book curriculum, as I was):
“In my passage home [from Scotland], having procured a celebrated book, (the Works of Nicholas Machiavel,) I set myself carefully to read and consider it. I began with a prejudice in his favour, having been informed, he had often been misunderstood, and greatly misrepresented. I weighed the sentiments that were less common; transcribed the passages wherein they were contained; compared one passage with another, and endeavoured to form a cool, impartial judgment. And my cool judgment is, that if all the other doctrines of devils which have been committed to writing since letters were in the world were collected together in one volume, it would fall short of this; and, that should a Prince form himself by this book, so calmly recommending hypocrisy, treachery, lying, robbery, oppression, adultery, whoredom, and murder of all kinds, Domitian or Nero would be an angel of light, compared to that man.”UPDATE: Jeff the Baptist linked - thanks!