Cyworld took off after it was acquired in 2003 by SK Telecom Co. (SKU), Korea's largest wireless service provider. The idea, of course, was to generate revenues. Although the service itself is free, when people add digital couches or TVs to their home pages, they spend real money. They swap cash for a digital currency called dotori (Korean for "acorns"), which cost 10 cents each. For instance, a digital couch costs six dotori. SK Communications, the subsidiary that runs Cyworld, chalked up a profit of $12.5 million on sales of $110.4 million, nearly half by selling dotori. The company expects sales to double this year.