I have long been intrigued by things that fold, hide and transform. Have a look at these pieces of British Campaign Furniture. They were designed for British military officers who had the luxury of travelling heavily with some of the comforts of home (most people would find it inconvenient to travel with filled bookcases for instance).
The leading book on this topic is British Campaign Furniture: Elegance Under Canvass: 1740 - 1940 by Nicholas Brawer. It's out of print and is highly coveted, selling used for around $300. I urge any benevolent readers with generosity streaks to feel free to gift it to this blog's author. It will make you feel great.
A bit of history from Brawers website:
If you want to purchase original pieces, check out the site of Christopher Clarke Antiques.
Folding bookshelf in walnut
This very beautiful campaign inspired piece is by NY designer Richard Wrightman. You can see other designs in the collection on his site.