A collaborative mapping project has been launched to build a database of bloggers who have been threatened, arrested or killed for speaking out online and to draw attention to the campaigns to free them.

So far, "Threatened Voices" has tracked 177 cases of threatened or arrested bloggers. The website features a world map with an interactive timeline plotting the threats and arrests.

The website is provided by the advocacy arm of citizen media site Global Voices.

To visit the website, click here.