Several health care Web sites continue to thrive in the growing online health information market, USA Today reports. One expert in global research at Hitwise notes that the number of health information Web sites has nearly doubled since 2005. Yet, WebMD and About.com, for instance, are thriving in the Web 2.0 era and "have carved important niches in a specialized market that is going gangbusters," according to USA Today. Though many early health care Web sites failed, WebMD, About.com and BabyCenter benefited from changes in consumers’ Internet use, the emergence of specialized online content and an Internet advertising boom. They also flourished under takeovers by media giants that took a hands-off management approach. According to WebMD, acquired in 1999by Healtheon, now called HLTH, the site had 40.8 million unique monthly users in the third quarter, up 26 percent from one year earlier. Touted as the second-largest medical Web site and purchased by the New York Times Company in 2005, About.com, meanwhile, reported a 28 percent revenue increase from 2006 to 2007 in part because of surging online ads. In addition, the site drew 8.4 million unique users in January, a 36 percent increase from January 2007, according to Nielsen/NetRatings (Swartz, USA Today, 2/18/08).