I abused my iPhone and it's got the marks to tell the stories. The most annoying though are the scratches on the pretty silver bezel, but as Lifehacker shows us, they can easily be eliminated using a kitchen sponge.
As you can see in the video, all that you really need to do is smoothly stroke the bezel with the rough (usually green) scrubbing surface of a kitchen sponge. Just don't forget to use masking tape to protect the rest of the phone. It's the simplest cosmetic surgery you'll ever do.