Just like the scene in "Miracle on 34th St" (the newer one) a Santa made a 6-year old's day when he learned sign language so that he could communicate with her and many other children!
I did this last year and it is not only cool but really gets the kids excited! You can have Santa send an email telling your kids to make sure they are good and that Santa is watching. It's personalized and really gets everyone in the Christmas spirit...