Is Google being outdone by Facebook? While Google's unique visitors still outstretch Facebook's by a rate of 3 to 1, Facebook has become a bigger source of traffic for some large websites, Ad Age reports.

With Facebook's user base growing at a double-digit rate since last summer, it's inevitable that the site would start referring users to other sites in droves.

Facebook now refers more people to gossip sites like PerezHilton.com and Dlisted.com, mom site CafeMom, Evite, video site Tagged.com, and Twitter, according to the latest data from Hitwise.

Much of the traffic referral growth can be attributed to fan pages, synchronized status updates, and the immense video and link sharing that takes place on Facebook.

Still, there's no rhyme or reason why some sites get more referrals from Facebook and others get more from Google. Since the beginning of the year, PerezHilton.com has received 8.7 percent of its visitors from Facebook, while 7.6 percent come from Google, Hitwise reported. Things are different at TMZ, which got 12.2 percent of its traffic from Google and just 3.8 percent from Facebook in the same period.