Microsoft founder Bill Gates is still raking it in.  He once again topped "Forbes" list of the 400 wealthiest Americans. He's worth a cool 72-billion dollars. 

The 57-year-old was followed by the Oracle of Omaha Warren Buffett in the 2013 rankings.  The average age of the super rich was 66, with only 32 of those selected younger than 48-years-old. 

Facebook founder Mark Zuckerberg was among the whipper-snappers to make the list.  He's 29-years-old.  (Metro Networks Inc.)