According to the comScore Media Metrix monthly analysis of consumer activity at top online properties and categories, the online classifieds category grew an impressive 35 percent in visits compared with March 2005, and 13 percent versus February 2006. CraigsList.org continued to be the category leader with 9.5 million visitors, up 12 percent since last month, and up an impressive 155 percent since March 2005.

Trader Publishing Company, publisher of Auto Trader Magazines, rose 10 percent over February to 8.3 million visitors, followed by Cars.com (up 28 percent to 4.2 million visitors) and Autotrader.com (up 9 percent to 5.2 million visitors).

Among the top 50 websites, Yahoo sites retained top ranking with 123.8 million visitors; Time Warner network was number two for the first time since October, attracting 116.6 million visitors. Wikipedia sites continued to attract visitors, moving up 10 spots to number 18.

According to comScore's "Ad Focus Ranking," the Advertising.com ad network retained its number-one position for the 23rd consecutive month. AOL re-entered the Top 10 by reaching 50 percent of all Americans online; AdDynamix.com jumped 16 spots to number 20. DrivePM had a strong debut in the Ad Focus Ranking, entering at number 14, reaching more than 48 million Americans online.

Consistent with previous years, the majority of March's web activity was seasonal, with spikes in the travel, genealogy, training/education, religious, sports/outdoor retail, classifieds and the auto categories.