Most banks now offer "overdraft protection," a service typically packaged as a courtesy for consumers, a little extra benefit to help you out.

But a new survey by the excellent Center for Responsible Lending shows that, looked at another way, overdraft loans are just another form of predatory lending by financial institutions which hurt the most economically vulnerable:

A nationwide survey shows that low-income people, single people, and many people of color are increasingly turning to borrowing money from financial institutions by over-drawing their checking accounts, racking up interest rates that can exceed 1,000 percent.

A telephone survey of 3,310 households done for the Center for Responsible Lending shows that a mere 16 percent of bank customers account for nearly three-quarters of all overdraft loans.

"A service created as a favor for customers has morphed into a harmful practice that traps vulnerable customers in debt," said Eric Halperin, a senior policy counsel at the Center. "Some banks now realize that trapping borrowers and charging them a $25 fee for a $20 overdraft loan is a pretty good scam."

Financial institutions are increasingly turning to fees to increase their income. Of the estimated $10.3 billion in overdraft fees Americans pay each year, the survey indicates that $7.3 billion comes from repeat borrowers.

This is no small deal -- it's one of many lending abuses that cause some $25 billion a year to be lifted from the pockets of the poor and working class by elite financial institutions (who are some of the biggest political contributors, helping stave off effective regulation).

Click here to read the full report on overdraft loans (pdf).