Douban is an open forum popular among college educated market for movie, music and book reviews. The majority of the content is accessible by unregistered users; therefore the 60 million+ registered users may be representative of a portion of its use.
Jiepang is a newcomer that is similar to FourSquare as a location based social media.
Momo is a recent entry in the Chinese social media landscape. Momo is a dating app.
QQ Instant Messaging service (800 million approximately) is popular with the under 18 target audience.
Qzone is a social networking site where users can write blogs, share photos, and listen to music. It is popular with the under 18 age group.
Sina Weibo: A cross between Twitter and Facebook, this microblogging platform allows users to include images and video, as well as longer comments. Weibo has more users than Twitter has world-wide. Approximately a quarter of Chinese citizens are members of Weibo.
Renren is considered China's Facebook is very popular with college students and the college educated market. Although there are 147 million registered users, only 31 million are active each month.
Wechat formerly known as Weixin is the up- and-coming social media channel to watch currently. As I walk around China it seems everyone has at least one cell phone. I won’t get into the differernces between the mobile market of USA versus China, but this — is a mobile voice and text app with social features like “friend discovery."
Youku and Tuduo are video sharing (aka YouTube) that merged last year. Interestingly, Youku is not constrained by copyright laws in China so they commonly have copyrighted feature films available to view in Mainland China.