Since it is easy to identify web users living in China, its possible to tailor web pages for that subset of users. Why not work out a way to insert modify web pages that are sent to China so that a header is inserted containing opinions from people in China?
Such a header could use AJAX, which allows contact with a server, so opinions could be refreshed and folks from China can submit opinions. SSL encryption would be nice too.
If enough web sites adopted such a scheme, it would be very difficult for the Chinese authorities to block them all without a big negative impact on access to valuable information. And some of them would always get through.
Of course, the problem is that each site has to go to the expense of doing this and that is probably why it won't happen.
Googling this topic, I see there's already a lot of thinking being done about various approaches.