Put stick-on decals on a picture frame and remove the back of the frame. Simple as that!
paint a piece of wood (could paint a solid color, or paint a design/pattern like this one), sand and distress/age the corners, then attach a regular picture frame on top. These are about $150 in gift/home decor stores.
Put decals on a picture frame, and leave off the back.
Cool idea to repurpose those inexpensive thrift store frames into cool vignette bookshelves...Links to Top 60 Furniture Makeover DIY Projects and Negotiation Secrets