This budget DIYsolution from the Queen of Good Things is genius in its simplicity and impact.
Martha's writers suggest mounting a rolling window shade on the underside of an open shelf and pulling it down over the shelf below when you want a more restful view of your open storage. A quick yank and it rolls back up to reveal your clutter.
"Shelf Shade", as Martha Stewart Living calls it, is a great way to make a room multitask. Open shelves make for super efficient storage in work and play rooms, but when the work and play are on hiatus, it's nice to be able to quiet things down.
Roller shades like these are available at most hardware stores and can be custom-cut to the width of your shelves.