Origami Design Secrets: Mathematical Methods for an Ancient Art by Robert J Lang is a one of a kind book.
Manuel Sirgo’s Cifocrania (or winged stick insect) is definitely a fine work of art. The crease pattern was also surprisingly easy for such a fantastic result.
The origami modular swan is made from 480 rectangles. Each rectangle is folded into an origami triangle with two flaps and two pockets. They can then be connected by inserting the flaps into pockets, then layering it all up to create 3D abstract models.
Bringing Origami to Life by John Montroll is a great book for starting out in origami. It was the first book I bought and it got me started nicely.