Video is another possibility. Definitely try to capture what you can while you can. I have only a couple of recordings of my first wife and one of my second. I would give anything to be able to hear the first one's harmonies again. The second one was just getting to the point of confidence in her own voice when she got too sick to continue.

Maybe you could help her get down an oral history of her family -- childhood, her parents, grandparents, etc. Something that can be passed down to future generations.

Just a couple of thoughts off the top of my head.

Mainly, though, let her know she is loved.