Judging a book by its cover

My favourite book cover is The Host by Stephanie Meyer. You can't tell properly in this picture, but the white ring around the pupil of the eye is metallic silver.

I love that they used a very simple image but put so much thought into it - in the story (and this isn't a spoiler) you can tell the aliens because their eyes shine silver when you shine a light at them.

I picked up this book a few years ago partly because I'd read the Twilight books and enjoyed them, and partly because I really liked the cover of this book.

What's your favourite book cover?