According to the folks at 41 pounds.org, the average person gets 41 pounds of junk mail a year (I don't know what they are going to do about their name if the average changes). Using their service, you can sign up to get your name automatically removed from most bulk mailer lists, significantly reducing the amount of junk mail you receive.

It's good for the environment since there is less waste, and it's good for you since you don't have to deal with all the junk. The only downsides are that they charge for the service... and it doesn't work on email :)