Sorry to have been gone so long, my friends.
Now, for your viewing pleasure — the greatest book cover of all time. And you can have a used copy of your very own for just $176.35 (plus shipping and handling)!
More terrible, horrible, no good, very bad, wonderful book covers (mostly genre titles — sff, romance, urban fantasy):

I think they’re pink?
- Something Awful — including The Color of Her Panties (Avon Books, 1992), the fifteenth book in the NY Times bestselling Xanth series (the description is also worth reading).
- A best-of list from Comics Alliance — including M.Y.T.H. Inc. in Action (Ace, 1991; go ahead, say the title aloud), The Princess Bride (Ballantine, 1975; a truly awful cover design), and Gladiator-At-Law (Baen, 1986), wherein corporate lawyers rule the world, forcing lowly criminal lawyers to fight to the death.*
- More on the tramp-stamp phenomenon in urban fantasy
And to keep things balanced, here are links to some actually very good book covers:
- Book Cover Archive
- More from Smashing Magazine
- The Art of Penguin Science Fiction — I wouldn’t say all of these are fantastic, but it’s cool to see how they’ve evolved over time and how Penguin has maintained or reprised many of the design elements.
- More about Penguin’s cover design history if you’re so inclined.
Kind of related — classic (and cult classic) movies reimagined as 60s and 70s book covers:
I Can Read Movies — some may be movies based on books, but this is a book cover for the movie, if that makes any sense. Highlander and the Japanese Willy Wonka and the Chocolate Factory (translated title: Mr. Wonka! Just Punisher of Coddled Children) are pretty great.
*Quick side note: Gladiator was co-written by Frederik Pohl in 1955. He has been an agent, an editor, and of course, an author. Today, Pohl is 92 years old and posts several times a week at The Way the Future Blogs. Very cool.