Child's name and date of birth on stackable rings. Have similar for my personal children(put all 3 on one ring)and grandchildren. I actually, need another ring. G-baby # 3 arrives in October! I love my rings.
Monthly picture on one side, text on the other about the month. Take it a step further by taking their picture with the same thing every month so you can see how they've grow and change. Maybe continuation of pregnancy book