I sometimes work with developers in China, it's pretty common for me to send a link to some tech info on a blog etc and then have to copy and email the content instead, since the site is blocked for them. Even one site I created myself, which has <10 visitors/day and barely any content was blocked at some point.
* http://en.wikipedia.org/wiki/Internet_censorship_in_the_Peop...
* http://en.wikipedia.org/wiki/List_of_notable_websites_blocke...
* http://en.wikipedia.org/wiki/List_of_words_censored_by_searc...