Great idea! They also make a wood moulding (yeah, I like the old-fashioned spelling because it doesn't also mean "growing fungus") that is called picture rail or picture moulding. They used to put it up by the ceiling (where a crown moulding would go) so you could avoid putting holes in plaster walls. It has a rounded top that accepts a special hook for hanging wires on that hold pictures and can usually find it at home centers and lumber yards/hardware stores. The little 1942 house I bought last year has some in a couple rooms and I love it. I want to add it to a few rooms, as well. Here is a link with photos and info of each the parts.
Picture Rail Moulding, hooks and cord: http://houseofantiquehardware.com/s.nl/sc.13/category.64/.f