MySpace is by far the fastest-growing top web brand in the U.S., followed by Google, which maintained double-digit growth, according to Nielsen/NetRatings; moreover, five of top 10 fastest-growing web brands were user-generated content sites.

Among the top 10 web brands - those with a minimum unique audience (UA) of 750,000 in July 2005 - MySpace was the fastest growing, increasing 183 percent, from 16.2 million unique visitors in July 2005 to 46.0 million in July 2006, according to Nielsen (pdf). Google was second, growing 23 percent, from a unique audience of 76.2 million to 94.0 million. eBay rounded out the top three, increasing 13 percent, from 51.1 million to 57.8 million unique visitors.

User-generated content sites, including platforms for photo-sharing, video-sharing and blogging, comprised five out of the top 10 fastest-growing web brands overall in July 2006.

Image hosting site ImageShack ranked No. 4 among July's fastest-growing web brands, increasing 233 percent, from a unique audience of 2.3 million to 7.7 million. Heavy.com, a video sharing site, took the No. 5 spot, increasing 213 percent, from 965,000 to 3.0 million unique visitors. Photo-sharing site Flickr followed at No. 6, growing 201 percent from 2.1 million to 6.3 million unique visitors.

Other user-generated content sites that made it into the top 10 fastest-growing web brands were MySpace, with a 183 percent year-over-year increase, and Wikipedia, with a 181 percent year-over-year increase.

"User-generated content sites have seen significant growth over the past year, owing in large part to their reliance on viral marketing," said Jon Gibs, director of media analytics, Nielsen/NetRatings. "They also benefit from their cost-effectiveness - the content is practically free."

Gibs continued, "Notably, the Associated Press also stands out, as a more traditional outlet innovating to keep pace with technology. The launch of its video offering earlier this year has driven significant growth as consumers seek streaming content to complement online and print news. In addition, benefiting from massive online and offline advertising, incentive pricing and reduced security concerns, HSBC has been attracting an increasing number of existing and new customers to online banking."