On today's Planet Money, we meet a single mother who makes $16,000 a year — and who managed to fund a vacation at a Caribbean resort with an interest-free loan from one of the world's largest banks. Edith Calzado gets credit cards with teaser zero-percent interest rates — then transfers her balance before the rate ticks up. She signs up for store cards to get discounts — then pays off her bill on time. She gets food stamps and lives in subsidized housing. Her son is doing well in school. She may be the single most successful and productive beneficiary of government assistance you'll ever meet. Note: This podcast was originally posted in 2010.