Did you ever wonder who pays for all the credit card junk mail that's been burying you lately? According to new advertisements appearing this week, all Americans do, thanks to credit card fees that you have probably never even heard of. The advertisements, placed by the Merchants Payments Coalition, a group of merchant trade associations seeking a more competitive and transparent credit card fee system, show how the big credit card companies use some of the billions they collect from the credit card "interchange" fee to pay for marketing campaigns, including a mountain of more than nine billion unsolicited credit...