For even more storage, consider hanging shelves up high that run the length of the room. You won't loose any floor real estate at all, and you'll gain a lot of storage space. Design Dozen: 12 Clever Space-Saving Solutions for Small Bedrooms
Hold on Tight bookshelf. A brightly-coloured aluminum cube and oversized wing nut serve as a sliding bookend which can be adjusted and secured wherever it is needed, whether your book collection is growing or shrinking.