I had that happen once. I placed a sign on my car that said. "I know who hit my car and I am going to hurt you." About a week later I was approached and told that if they had a pen and paper at the time they hit me they would have left their information. I said whatever, and took the information and got my car fixed. It was pretty fucking cool, I did not think it would work, but the little bookworm must have got scared and fessed up. Try it, chances are whoever hit you does not have any balls, otherwise they would do what is right and ethical.