Yearly photos w/ interests noted. Make up a few pages in photoshop or an editing program of choice, and create a printed 8x10 book. Give to your children when they graduate as a gift...I would use a few head shots and definitely lifestyle candid shots to get the real feel of what they were like at each age.
Button Letter Wall Decor. Why not use Sharpie to draw the initial for each child's name, then have them glue items inside for a personalized collage!