Indeed, once people go onto a Web site to play fantasy sports, they tend to linger. Fantasy Players spend an average of roughly 30 minutes on the Yahoo! site per visit, longer than people spend on Yahoo! News and HotJobs, according to comScore. Yahoo! saw a 42% increase in 2004 in the number of people who purchased some sort of service related to fantasy sports. Players also tend to remain loyal to their sites, making them an attractive audience for advertisers. The enthusiasts, who are mostly men, have yearly household incomes of $72,750, about 40% above the national median, according to the Fantasy Sports Trade Association. People spend about $100 a season on entry fees and play in an average of two and a half leagues, according to the association's survey. It estimates that about 13 million adults have played fantasy games in the past year. Beyond Yahoo!'s quest for ad dollars, fantasy football offers a chance to introduce people to more features, said David Katz, head of Sports and Entertainment for Yahoo! Media Group, which includes fantasy games. "You are talking about some of the most engaged users that you can find on the Internet," he says in an interview. "This is the kind of thing that sponsors don't need a lot of cajoling into. From a sales standpoint, it has been a terrific experience." Yahoo!, based in Mountain View, Calif., doesn't disclose how much it earns from fantasy sports. As of June, the company had 10.1 million of what it called paid relationships, people who paid it for some sort of service. The biggest chunk of those fees comes from Yahoo!'s co-marketing deals with telecom carriers in which they sell each other's services, and from the company's premium email service, Pykkonnen says.