Place painted foam board in the back of the bookcase, giving the look of a painted bookshelf w/out the commitment. Love this idea for a small book shelf next to couch. Good way to use yellow without committing to it in a big space.
Small Space Secrets: Swap Your Bookcases for Wall Mounted Shelving. Here's a creative shelving arrangement that uses a deeper shelf at bottom to create a sort of bench. The bench can serve as extra seating for parties, or as a display space.