Unique Book Characteristics

It is not always the story, setting, or characters that stick-out to me. Sometimes it is certain unique characteristics.

Here are just a few examples off the top of my tired brain of characteristics that I loved:

Kurt Vonnegut Hocus Pocus: Not only do I fantasize about being thrown into a library tower prison, but Kurt had the character write on pages of books. One page just said, "Cough, cough." Brilliant.

The Book Thief by Markus Zusak was narrated by DEATH. It was an interesting choice that wove together the whole book.

In Margaret Atwood's The Edible Woman Atwood changes the point of view as the main character begins to "lose herself." Subtly brilliant. Love me some Atwood.

Off-Trail: Trail Swap by Michele M. Reynolds she writes a short, behind the scenes book with the characters of Trail Swap. (Okay, this is my book. You caught me.)

What books stand-out in your mind?
What other unique tactics do you use or have you read?