User-powered "Web 2.0" sites like Flickr and YouTube have little participation, yet visitors who like to watch rather than create have spiked 668 percent in two years, according to Reuters.

Visits by Web users to the category of participatory Web 2.0 sites account for 12 percent of U.S. Web activity, up from only 2 percent two years ago, the study showed.

A tiny 0.16 percent of visits to Google's top video-sharing site, YouTube, come from users seeking to upload video for others to watch, according to a study of online surfing data by Bill Tancer, an analyst with Web audience measurement firm Hitwise.

Similarly, only two-tenths of one percent of visits to Flickr, a popular photo-editing site owned by Yahoo, are to upload new photos, the Hitwise study found. Web 2.0 photo-sharing sites now account for 56 percent of visits to all online photo sites. Of that, Photobucket alone accounts for 41 percent of the traffic, according to the Hitwise data.

By analyzing who's using them and how, Hitwise named six Web 2.0 companies it thinks will one day achieve hit status. The firm looked at the usage of patterns of the same online groups that made sites like Flickr, YouTube and Wikipedia the successes they are today. The list they came up with is:

• Yelp - Goods and services ratings from consumers
• StumbleUpon - Site recommendation
• Veoh - High-definition video sharing and publishing
• WeeWorld - Avatar creation
• Imeem - Online self-promotion
• Piczo - Customizable website creation