The inevitable ding. When the ding isn't structural, like what you are talking about, I'm a big fan of 5 min epoxy from your local hardware store. It's quick, easy and cheap. It will turn yellow pretty quickly, so if cosmetics are important, you'll want to try and dye the epoxy, or select one of the specific ding repair products. I found this list at La Jolla Surf - pretty extensive:
Ding Repair Kits listing (Message edited by surfdad on September 02, 2008)