If I'm making it for myself for a wall hanging, I usually use muslin for the backing and just write my label on it. As you say, no one will see it.
Originally Posted by Lobster
But why for a wallhanging, where you will never see the back? Bed quilts, fair enough (though I'm not sure it's worth making the back intricate, a co-ordinating colour is my preference too), and sofa or baby quilts, definitely make the backing interesting.