How about going to a pottery painting place and making a special frame to hold a picture of the baby? I think the keepsake box and handprint/footprint kit are great ideas, too, along with the special little gown.
She may already know this, but there are volunteer photographers who will be on call to come to the hospital and take pictures in situations like this, when the babies are expected to be stillborn or to not live very long. That may be something she would appreciate later.