We recently inherited some shelves for our office/playroom from Josh's parents. They were built-in to their office, so they aren't a perfect fit here. Mainly, there was one side that fit against their wall so was left unfinished. Here, there are about three feet between where the shelves end and the window seat begins. I thought that three feet could make a lovely reading nook for Smalls (in like, what, 3 years? when do they read?), but I hated the look of bare particleboard.
So lookit what I did:
I cut down some cork tiles to fit and adhered them with foam stickers and upholstery studs. Then I tacked ribbons onto the center of each tile and hung Dash's art from clothespins on each ribbon. Later, when he can be trusted, Dash can use thumbtacks to tack up whatever he pleases. Whole shebang cost less than $30 and took 2 hours, tops.