Groupon (Est. 2008) has 230 websites in 29 countries and 15m subscribers

"The most successful is Groupon (a combination of the words “group” and “coupon”, which buyers print out to pay for their service). Although the firm launched only in late 2008, it already operates some 230 local websites in 29 countries and boasts 15m subscribers. Flush with money from investors, it has embarked on a global land-grab, buying Groupon clones in other countries, such as Germany’s CityDeal.
Groupon is more about people than technology. It grew out of The Point, a Chicago-based website that offers tools to organise collective action. The firm employs a worldwide sales force of nearly 2,000 to identify interesting local merchants and 150 writers to describe the offers. It wants to be the company that finally allows small businesses to participate in e-commerce, explains Rob Solomon, its president."
Source:  The Economist, 9th September 2010