I had an empty corner behind my desk which was angled into the room. I'd hung small pictures in this space, but the corner still seemed barren. I also tried placing a tall, fake tree in the corner, but it kept hitting me in the back of my head every time I pushed away from my desk.
A couple weeks ago, I decided to install triangular shelves, and it created a great space for books and pictures. I've since added down-lighting to brighten the corner and highlight the display.
It was a fun, inexpensive project.