• by Gavin O'Malley  @mp_gavin, October 2, 2008

The Beijing Olympics, football season, and an influx of female sports fans drove a 26% year-over-year increase in unique visitors from worksites to online sports destinations in August, according to new data from Nielsen Online.

The number of unique visitors at work visiting sports destinations online increased from 33.4 million unique visitors in August of last year to 42.3 million unique visitors two months ago, Nielsen found.

"With broad interest in the Olympics, and the ramp-up of the college and professional football seasons, August was a busy month for online sports fans," said Jon Gibs, vice president, media analytics, Nielsen Online.

In particular, NBC Olympics attracted significant traffic at work during the month, reaching 20% of the active at work Web population, or slightly more than 13.8 million unique visitors.

The breadth of Olympics content that NBC provided online contributed to people not only visiting the Web site, but also staying for extended periods of time, with the average visitor spending 57 minutes and 7 seconds over the course of the month, according to Nielsen.

Yahoo Sports, meanwhile, was the number one online sports destination at work in August, with 18.7 million unique visitors, growing an impressive 112% year-over-year.

Web properties, ESPN and FOX Sports on MSN came in second and third, with 11.9 million unique visitors and 7.7 million unique visitors, respectively.

Among the top 10 sports sites, Fantasy Sports Ventures Network was the fastest-growing, increasing 285% from one million unique visitors to 3.9 million this past August.

"The increasing popularity of fantasy football also helped drive the impressive growth for the sports category in August. Over the past few years, fantasy sports have been one of the key drivers of consumer engagement in the sports category. In many cases, fantasy sports have become more popular than the sports coverage itself," Gibs said

. Of particular note, the number of female unique visitors at work to sports-related Web sites in August grew 37%, compared to the same period in 2007, outpacing the percent increase in male visitors by 76%.

The number of women increased from 12 million unique visitors and a unique audience composition percentage of 36% in August 2007 to 16.4 million unique visitors and a unique audience composition percentage of 39% in August 2008.