Storage would be a logical option.

Don't know if this would work for you, but the first thing that I thought of was bookshelves with a rolling ladder. Something like this with shelves to the front and storage behind.

Thank you, Madden, Slick & Bontempo! That is gorgeous and I love the extra railings with the bookshelves! Just so I'm clear, the person climbing the ladder would be able to hold onto the railings on the bookshelves while crouching a bit so they would fit in the short ceiling height, right?

Yes, That's the way I see it. The ladder would roll back and forth to access whatever is on the shelves and if you needed to get to the storage behind, you could grab the rails attached to the sides of the shelves and crouch to get in.