This is the perfect place to put a pull out bed! I always look at those beds and thing they're impractical because it's too hard to leave all of the open floorspace needed for one but I'd happily do it for this library/reading space.
Gallery of Arthouse / Pominchuk Architects - 13
Mini library + wrap-around desk = great idea for small space
office in a walk in closet
Modern home office in the bedroom
book shelves & large window and window seat - I wish I had the room for this.