In my last piece on mastering I mentioned a friendly little game played by clients called The "Make My Record LOUDEST Of All!" Game." In this highly competitive blood sport, clients beg, threaten, cajole and extort the mastering engineer to get him/her to make their particular mixes sound louder than any other CD on the planet. They often bring in their favorite LOUD CDs and say, "Beat this!" Lotta fun, especially when you've got a stack of unpaid bills.
Article: Taming Wild Mastering Levels