First, and most importantly Crafty Crafty tells you how to make your very own pair of ruby slippers.
Coolest Homemade Costumes has a ton of ideas for making Pippi Longstocking costumes with photos and tips from readers.
Fun-Frugal-Mom.com shows you how to make an adorable no sew puppy costume. You could easily do it up in red and you'll have a cute Clifford costume! (She also has cute ideas for Jack & the Beanstalk and Rapunzel.)
Wikiopens has some great ideas for Charlie and the Chocolate Factory characters including Willy Wonka, the Oompa-Loompas, Charlie Bucket, and Violet Beauregard.
Ehow has instructions for making an adorable Madeline costume.
If you're good with a sewing machine, That Costume Girl shares some patterns that would be good for a Laura Ingalls Wilder costume.
Kimberly at Seven Thirty Three made a cute Little Red Riding Hood costume.
And there is the most adorable Book Fairy costume tutorial over at Lilliedale. You've got to go check it out!
This list is just those I could think of that would be fairly cheap and easy to put together (and that mostly require no sewing). I'd love to hear your ideas!
Linking to Life in the Motherhood Lane