What you need is Hallowindow. Mark Gervais created a great DVD that will keep the tricksters away!
He pins a sheet over the windows inside the house and aims a projector at the sheet. The text is reversed out on the DVD so that the copy can be read from the street.
He's been doing this for two years and has sold out his supply for this year. He promises more by the beginning of November so you can get an early start unnerving the kiddies in the neighborhood!