It's fun to turn your Christmas tree into a family photo album! Select a baby picture of each member of the family to place in little hanging frames. The grandkids can find themselves first, and then try to identify everyone else.
For a more old-fashioned feel, the photos can be scanned, sized, and printed in black-and-white (a copy shop can do this).
To make your own, have your kids help select a baby photo of each family member.
Then simply place them in small ornament frames, seasonal items available at craft stores, and hang them on the tree.