My cup runneth over with beautiful (I think) and colorful art work from the kids. We've hung a simple cable system the entire length of one wall to display the masterpieces. But we also love this idea shown above.
It looks like a simple piece of trim, or you could use plain wood, affixed with clips. The end result looks very neat and the added bonus is the little ledge made by the wood piece can act as a shallow display shelf. This is great for displaying schedules and school calendars as well.
Image: Sweet Sweet Life