Two recent cases in China showed twitter (actually, it's state sponsored Chinese-clones because twitter is barred by the authority) could be one WMD for responsible Chinese Internet users.
In Jiangxi Province, an official eviction went wrong when three of the residents set themselves on fire in protesting the procedure. Although there are hundreds of police, paramilitary forces and even an ambulance at the scene. The senior communist officials order the demolition went ahead, and policemen blocked relatives and bystanders to rescue the burning individuals until they shrank to black carbons. The deceased had a dispute with the government on the proper amount of compensation for the building. However, it turned out as now we finally know, the eviction was not even lawful. There was no eviction orders from the court nor the local government. Local government jailed relatives to stop them from making a scene, but two were able to fled as far as the women's restroom in a nearby airport on the way to Beijing for a petition. The airport was not operated by the aforementioned local government, so although they summoned an army of public employees to surround the restroom, the two women were able to broadcast their situation online before they were taken away by force. The online broadcasting triggered a mass twitting phenomenon while the messages were followed and forwarded millions of time, which triggered the network monitoring agency's attention of the central government. The agency's evaluation of the incident is that it mounts to the scale of social stability level so that it should be handled carefully. The central government ordered the local government to release jailed relatives and to renegotiate a fair compensation for the demolished building.
Another incident happened in Beijing. An author was arrested by police in Shaanxi Province because he published an investigative report of people's sufferings on a state project. Although the project had been over dozens of years ago, thousands of people are still homeless because their land were taken away for the project and then reassigned to other people. Also thanks to mass twitting and forwarding, the author was granted a bail.
Although you can vote for the government officials or your representatives, but you do can twit, follow and forward. A few clicks might help save some good people's life. There is no excuse for not doing that.