• By Roberto Rodriguez  As they keep interest rates near
historic lows, Federal Reserve chairman Ben Bernanke and other
U.S. officials are a borrower’s best friend. But for retirees
and other income-oriented investors, the super-low rates are a
financial nightmare.  Portfolio mainstays such as U.S. Treasury
bonds and investment-grade corporate and municipal debt just
aren’t producing enough income. That has prompted—or forced—many
income investors to look farther afield.