Actually, fees can drive as much as half a bank's revenue, and overdraft fees are typically the largest component of that income.  These fees are almost entirely driven from checking behavior of Americans earning less than $50K a year.  You would be shocked at how frequently overdrafts occur for a customer with a low balance.  These fees can add up to hundreds of dollars a year on average for low balance customers.  In fact, they are among the primary reasons why "Free Checking" is an attractive offer for big banks.  (Hint: it ain't really free.)<p>There is serious congressional concern about the inherently predatory nature of overdraft fees.  However, with Dodd's impending departure from the Senate it appears that the banking lobby will prevail in avoiding legislative restrictions.