Craig Newmark,
Founder of Craigslist

and

One of the oldest and best known examples of social networking is Craigslist.org. With social networking Web sites, the network itself becomes a database of information for each user. Users create and build their own circles of contacts and discussions, and as people join and use the network for other reasons they add more details to the network database and it becomes more useful to them. "People feel connected (on Craigslist)," said Craig Newmark, founder and chairman of Craigslist.org

With a presence in 39 markets, including the U.S., and approximately 84 million active users worldwide, eBay has changed the face of Internet commerce. In 2007, the total value of sold items on eBay's trading platforms was nearly $60 billion. This means that eBay users worldwide trade more than $1,900 worth of goods on the site every second.