As a child I recall a Christmas where all the presents I received from Santa were marked with a tiny little sticker that said "Made By Santa". That sticker idea has stuck with me (no pun intended) and over the past few Christmas's, my wife and I have recreated a similar sticker to use for our childrens gifts that we call "Santa Stamps".
We like that these stamps add to the mystery of Santa and the big guy leaving gifts under your tree. Beyond that, we have found that designing the stamps to be color coded, they help out A LOT when you need to quickly look under the tree and figure out which gift goes with which child. With our variety of 4 stamps and colors, the sticker is not only fun but also functional!