The Paper Bag Princess by Robert N. Munsch

One of the reasons this story is great is because its one of the few books where the story doesn't end with the girl getting a guy. Princesses and romance go hand in hand, even when the princess is a tough, adventure-seeking, swash-buckling tomboy, for the most part they end up with a guy. In fact stories with female protagonists that don't end up with a guy could probably be counted on one hand, its a huge part of our cultural perception of women and their happiness. In this one she flips the guy off and walks happily into the sunset by herself. 

Especially at a time where stories like this are competing with Barbie and Bratz for our young girls, and I guess the boys who think the girls are like that, this is one of the more popular stories where the princess is smart and gutsy and gets things done to her satisfaction. It's not even close to the only story like this, but as I say, one of the more popular. It teaches kids that girls aren't delicate pieces of glass and can yell out 'you are a bum!', which is funny and has none of the pretentious ideas about making little girls into little women instead of letting them be little girls. Also, it has been commented that the story isn't the most literately complex, to those people I say you obviously haven't heard it live. It doesn't need to be a novel to get the message across. A lot of people I know and I see drill into their kids the need to always be challenging themselves, which is good, but they also don't let them do non-challenging things for fun, which is semi robotic. I mean they're just kids, who cares if its a line a page and that line isn't the most mind blowing sentence in the English language. If it fun, its ok. Loosen up a bit.