Seramark or Phototex wall graphics. Christmas trees with sets of vinyl decals so you can decorate them, fireplaces, Christmas lights, Satan, elves, reindeer, candy canes, snowmen (You can actually make one and take a pic of it and use that), mistletoe, baby Jesus and the nativity scene, draydels, manoras (you can tell I was raised Christian and not Jewish by my seplling of those last 2 words), Kwanzaa related stuff, etc. It makes it easier to decorate the house AND to clean up when the season's over!
Actually thinking of designing some stuff to use for the same type of idea but Halloween instead of Christmas.