• by Laurie Sullivan  @lauriesullivan, March 8, 2012

Marketers could find a gold mine in Pinterest, but could have challenges with copyright laws. Last month the site sent more referral traffic to publishers than Google and Twitter, according to a traffic report released this week.

Shareaholic, which aggregates data from 200,000 publishers reaching more than 270 million monthly unique visitors, estimates that in February Pinterest referred 1.05% of visitors to publisher Web sites, outpacing Google at 0.91% and Twitter at 0.82%. It turns out that Pinterest outpaced LinkedIn, Google Plus and YouTube combined in referral traffic.

Facebook at 6.83% and StumbleUpon at 1.29% were the two sites that outpaced Pinterest for referral traffic.

Google Plus referral traffic held steady at .05% of all traffic from January to February. Putting that into context, Shareaholic found that was the same traffic percentage referred by Yahoo Answers.

"Referral traffic is interesting to follow," said eMarketer Analyst Kimberly Maul. "Pinterest and StumbleUpon allow you to go from site to site to site quickly, but Google, Facebook and Twitter require a little more effort because you have to click the 'Like' or the 'Share' button."

Pinterest isn't only driving more referral traffic to publisher Web sites -- content seems to keep users on the site longer. An eMarketer report reveals that Pinterest users in the U.S. spent on average 88.3 minutes on the site in November 2011. Compare that with Facebook at 394 minutes, Tumblr at 141.7, and Twitter at 24.4.

Maul points to comScore numbers that estimate time spent on Pinterest rose more than 500% between May and October 2011. She wrote that "comScore pegged unique U.S. visitors at 11.7 million in January 2012, with the average visitor spending more than an hour and a half on the site that month."

The opportunity for marketers lies not only in posting information from their company, but also easily pinning photos and information from partners. The challenge, however, has become copyrights -- determining who holds the copyrights to the photos, Maul said. "With Facebook you post your own photos, but with Pinterest and Tumblr it's more about sharing things that's interesting," she said. "There must be a way to create the author of the photo."

Referral traffic remains one part of the equation. The other belongs to organic search traffic that dominated with more than half coming from search engines Google, Yahoo and Bing.