Top social networking sites like Facebook and LinkedIn may be well-established, but that doesn’t mean they’ve stopped growing.
Nearly half of the biggest social networking sites are also among the fastest growing, according to data released Wednesday by Nielsen Online.
These top sites have also expanded beyond the youthful audience the social networking space initially captured — to find a place in older visitors’ professional lives.  Facebook, LinkedIn, and Reunion.com are most popular among visitors ages 25-34, 35-49, and 55-64, respectively, Nielsen reported.

Rank
(by Sept. YOY UA growth)
10 Fastest Growing
Social Networking Sites: Sept. 2008
Sept. 2007:
Unique Audience …

Baidu, China’s leading online search engine, was the most popular website in China in early September, according to data released Friday by CR-Nielsen, Nielsen Online’s joint venture partnership in China with Beijing Zhongqian Wangrun IT Co. Ltd.
Between September 8 and 14, Baidu attracted 171 million unique browsers — more than double the volume of Google China, which drew 81 million unique browsers during the same period.
CR-Nielsen is the first company authorized to support the delivery of standardized Internet measurement and analysis services in China — home to an estimated 253 million …