New books coming that look interesting. I'm always glad to see kids enjoy stories where the characters are complex (e.g. Lord of the Rings), where not everybody is nice (I freaking *hate* Dora), where characters develop (think Eustace in Voyage of the Dawn Treader), or when we just plain enjoy some mean and/or depressed guys (Lemony Snicket). Over here we're fans of Rick Riordan's Peter Jackson series (books, audio books, and movies) and one of the reasons I like it is because the characters aren't particularly child-safe and unidimensional. There's real bad, scary stuff happening in those stories, and yeah, there's the whole Greek mythology component that's also fun. I mean, hey, classical education is becoming fashionable, woo-de-hoo.
Obviously each child is different and it's up to parents to determine what level of creepiness is too much, but by all means expose the little ones to complex, scary stories. They should end mostly well, in my view, but they should be genuine squeakers. Because life isn't Dora (thank goodness).