When I first heard about ebay, I said, "Nonsense! That will never work. Nobody's going to send money to some random person they encountered on the Internet in hopes that person will out of the goodness of their hearts actually ship them some merchandise." A lot of people thought this. We were all wrong. Wrong, wrong, wrong. Ebay made a big bet on the cultural anthropology of human beings and won. The great thing about ebay is that it was a huge success precisely because it seemed like a terrible idea at the time, and so nobody else tried it, until ebay locked in the NetworkEffects and first-mover advantage.
Online classifieds, general market site.
Also own PayPal so have the money thing too.
See also :