Using a whole wall as a bookcase can look overwhelming, so try dividing the room with a fireplace.
An unconventional bookcase design like this one becomes art for your wall.
If one wall is dominated by a bookcase, be sure that the paint color is light so that the space still looks open.
Surrounding a window with a bookcase on both sides is a great use of space, and the arches at the top add visual interest.
A bookcase built into an entryway wall is perfect for showcasing pictures.
Images via Flikr
Share ideas and built-in bookcase pictures here.