Princess Mononoke his the second-latest movie from Hiyao Miyazaki; the latest is the also-excellent Spirited Away. He's been showing a trend to more mature themes, lately; My Neighbour Totoro, for example, you could happily sit your four-year-old down in front of, and enjoy it along with the sprog. But there are aspects of both Mononoke and Spirited Away that'd cause the more paranoid of parents to shy away from.
All Miyazakis's movies are excellent. Watch them all.