A previous poster mentioned the Finnish system of traffic fines. It's an interesting attempt to equalize the impact of monetary punishments by pegging it to income. It makes sense in principle. I remember when I was younger and had little money; it hurt when I got fined for speeding or something like that. Today, it's a rounding error in my checking account. In Finland, they fined a guy something like $100,000 for speeding because his income was so high. Maybe Huckleberry Finn can comment on how effective this has been. It would be very difficult to implement, and will never happen here, but it's an interesting concept.
The system is used for all kind of crimes which you can get fine punishment, not only for speeding. I can't say much about its effectiveness because it has been used a long time.