While social websites like MySpace and Facebook are growing like gangbusters be watching for niche social sites to grow, especially in areas like sports. BusinessWeek reports SkiSpace has jumped to 10,000 members in the month since it launched. BW goes on to report, “Sports social networking would seem to be a natural since fans are tribal by nature. And if the sports world has taken a while to capitalize on the obvious, that’s changing fast. In the past year pro leagues—including the NBA, NHL, Nascar, and PGA Tour—have opened up their sites, allowing fans to post comments on message boards and create interest groups.”