• by June 18, 2007

CENTRO, which places national display ads onto local newspaper Web sites, stormed into comScore Media Metrix's top 50 ad rankings for May--entering at number 20, and reaching 42% of the U.S. online population. Another big mover in May was Undertone Networks, which more than doubled its reach to 30%, and moved up nine positions to number 29.

In the top ten, Yahoo moved up one spot to number two, and Blue Lithium, two spots to number six. Advertising.com was number one for the 37th straight month--although its reach dropped one percentage point to 87% of all online users. The remainder of the top 10, in order, were: ValueClick, Tribal Fusion, Casale Media Network, Google, AOL Media Network, Connexus TrafficMarketplace (formerly Vendare Netblue) and Specific Media.

May traffic to many sites benefited from the start of the 2008 Presidential debates, summer season movie premieres, and Mother's Day, comScore said.

Political sites were the top-gaining category in May, increasing 17% from April to 9 million unique visitors. Politico.com, which sponsored the May 3 Republican debate, skyrocketed 162% to 648,000 visitors. MoveOn.org, which featured an online petition against gas price increases, rose 246% to 689,000 visitors. Candidate-wise, BarackObama.com won with Web users, up 13% to 298,000 visitors, followed by HillaryClinton.com, up 3% to 217,000 visitors.

The movie ticket category gained 12% over April, to 40.8 million visitors, including a 55% increase at MovieTickets.com (to 5 million visitors) and a 50% increase at Fandango.com (to 7 million). The "retail movies" category rose 7% to 27.6 million visitors, and movie social networking site Flixster.com zoomed 65% to 4.5 million visitors.

Other hot growth categories, fueled by Mother's Day, included "flowers, gifts and greetings," up 11% to 35.6 million visitors. Leading this category was Trilegiant Corp., whose sites include 1-800-FLOWERS.com, which surged 365% to 5 million visitors.

Turning to the 50 most-visited Web properties during May, the biggest mover for the second straight month was ARTISTdirect, a group of sites featuring multimedia music content--climbing six positions to number 35, with 13 percent more unique visitors than in April.

Yellowpages.com moved up five spots to the number 33 position, and Photobucket moved up four positions to number 29. The top six positions, as in April, were in order: Yahoo Sites, Time Warner Network, Google Sites, Microsoft Sites, Fox Interactive Media and eBay. Amazon Sites and Ask Network both moved up one position to numbers seven and eight respectively, followed by Wikipedia Sites and New York Times Digital.

In addition to Trilegiant (#1), Flixster (#4) and Fandango (#5), the top 10 gaining properties in number of unique users reflected the continuing growth in popularity of online videos, with ManiaTV.com at number three, up 68%; TopTVBytes.com at number six, up 48%; and ABC.com at number seven, also up 48%. Social sites Snopes.com (rumors) and Slide.com (slide shows) were numbers eight and ten, up 42% and 33% respectively. Mars Inc. was number two--up 76%--and Glam Media number nine, up 42%.

The category showing the largest user gain in April was gay and lesbian community sites, up 24% in unique users and led by Planetout.com, followed by e-cards, led by Evite.com; computer hardware retail; flowers/gifts/greetings retail; downloads; women's community sites, led by iVillage.com; entertainment news; food retail; job search; and personals sites, led by True.com.