Here are a few literary based costumes (click on the pictures to see the links):
First off, a little Dr. Suess:
One of my favs.
Arthur by Marc Brown:
Can't get enough of Mo Willems' Pigeon books:
Click on the picture/link. There's another picture of him with his mom dressed as a bus driver.
A classic, Pippi Longstocking:
A Bad Case of the Stripes. Clever, eh?
What's all this Halloween Sewdown about?