My sister recommended this to me and now I am recommending this to you! It's a little a book called Elf of the Shelf. It retails for 29.95 (I got mine on ebay and it came with free shipping). The kit comes with the cutest rhyming Christmas story and a little elf doll.
The story is about this elf who watches you all day and flys home at night to report to Santa all your naughty and nice behavior. Each morning he is in a new place in your house and the kids find him in the morning. On Christmas Eve he flys home with Santa with promises to return next year around Thanksgiving.
Nothing like a mild case of paranoia to motivate good behavior! Whatever works :) xo, Brie