Not an easy DIY, but such a cool idea. How to build a pivoting bookcase that hides a door. Great Idea for adding some beauty to random closet doors. I could see this becoming a great "hidden" fort for kids in the cupboard under the stairs.
fun idea! (edited the link to actually go to the original blog post that this image is from; also here is a direct link to a close up photograph of how these awesome book/magazine holders are made: s3.amazonaws.com/... )