I see a lot of "almost" bookshelves. They hold books and look "design-y" but they waste energy and space. If you are really into books, it's not about the cute shelves. It's about the books. Make that space hold as many as it can.
Wall mounted corner shelf: I like the design and how it attracts the eye, but I picture this made with reclaimed pallet wood doubling or even tripling up planks that would give it more depth and character.