Amnesty highlights the case of Shi Tao, sentenced to jail by Chinese authorities for 10 years for sending an email.
The organisation said around the world Internet cafes are closed, PCs are seized, chat rooms are scrutinised and blogs are debagged. Search engines are censored.
The campaign, at Irrepressible.info, says multinational firms like Cisco, Yahoo, Google, Microsoft and Sun Microsystems have colluded in Internet censorship.
Amnesty said it is starting an email campaign to get IT firms to "stop putting profit before principles". It will target countries which seek to limit the freedom of the Internet, and try and get people released jailed for using the web as a "force for freedom".
It is working with the Open Net Initiative to show the extent of net filtering, with a map here. ยต