Site maintained by Jason Ng Google Policy Fellow at the University of Toronto’s Citizen Lab and author of Blocked on Weibo, discusses his work and other censorship issues relating to social media and China. Includes lists of blocked words.
For other information try.
Herdict a user-driven platform for identifying web blockages as they happen; from the Berkman Center.
Great fire an online monitoring site relating to China.
Freedom on the net reports from Freedom House the latest report is now online.