As the story goes, 60 years ago, Frank McNamara, the founder of what's considered the first credit card, was eating out at a restaurant, and when the check arrived, he realized that he had not brought along his wallet. The embarrassing situation led him to eventually create the Diners Club card, which allowed members to pay restaurant bills monthly. The card itself was wallet-sized and made of paper and wasn't any fancier than a library card. But the idea behind it-a third party facilitating a "buy-now, pay-later" process-was revolutionary.
Click through The Big Money's slideshow on the history of the credit card.