When Zhong Jizhang, an engineer in the southern Chinese city of Guangzhou, discovered that a company building an extension to one of the city's underground lines had cut corners and breached safety standards - and had then produced a fake report claiming the problem had been resolved - he knew just what to do.
He published the information on his blog.
Within days it had been picked up by the local media and the city government launched an investigation into the case which bore out his findings.
In the northern province of Hebei, meanwhile, a 22 year-old driver knocked down two female students on a university campus, apparently while travelling at many times the speed limit. One of the women died from her injuries.
When students and security guards tried to stop him leaving the scene, the man yelled at them not to meddle with him, since his father was a local police chief. It was the typical response of the privileged and powerful in China's system.
Yet the young man's belief that this would protect him turned out to be badly misplaced: news of the incident was posted online and the story picked up by mainstream media. Angry internet users launched an online search to track down the man's identity.
Within a few days the case was being widely debated in media and websites around the country - with many commentators holding it up as a prime example of the arrogance and abuse of power practised by some influential people in today's China.
These two cases are typical of the growing use of the internet in China to expose misdemeanours and abuses.
Internet users fight back
In a country where the media, despite increasing commercialisation, remains under the ultimate control of the ruling Communist Party, and where other types of civic space are limited, the internet has rapidly developed into one of the major channels for Chinese citizens to exchange information and express their views.
The transformation has been startling: at the turn of the 21st century, China had around nine million internet users. Today it has more than 420 million people online, and over 200 million bloggers.
The country now has the world's largest networking tool, Tencent's QQ, and has seen the rapid growth of web forums connecting people with shared interests - pregnant mothers, animal rights supporters, car enthusiasts - and of chatrooms and bulletin boards where ordinary people frequently post views on social issues, including cases of corruption - at least at the local level.
It all adds up to something of a social revolution in a country where few people even had a telephone until the 1990s.
As Isaac Mao, one of China's first bloggers, and a former fellow at the Berkman Center for Internet and Society at Harvard University, puts it: "In China information was always controlled by a hierarchical system - now we have an alternative structure, where people can go beyond geographical boundaries and connect based on common interests. It's like a new social fabric."
Not for nothing did Professor Xu Rongsheng, a scientist who set up China's first web connection in 1993, describe the rise of the internet in China at a recent conference as a "nuclear bomb" which produced an unprecedented "information explosion."
The rise of the internet has also had a significant impact on China's conventional media, which was traditionally heavily controlled and seen as little more than a propaganda tool of the ruling Communist Party.
The advent of websites gave journalists on state media more space to publish stories which would not normally be approved for publication in their newspapers.
"Don't read the paper, look at the website," was how one journalist from the party mouthpiece the People's Daily put it in the late 90s.
Soon, even official websites were reporting news much faster than conventional media, particularly in the case of accidents, disasters, even bomb and arson attacks in far-flung parts of the country.
And the web also eroded the power of local officials to keep a lid on bad news.
Previously they had only to issue a directive to the local media not to report on a mining accident in their area, for example. Now local journalists could send the story to a website or a newspaper in another part of the country and the internet would allow it to be seen around the nation - including by the central authorities in Beijing.
It has all contributed to radical changes in China's media culture.
The government eventually changed its directives on the reporting of accidents and disasters, allowing for much more open coverage.
Newspapers also began to emulate the more lively style and look of China's popular websites.
And the internet has arguably also given newspapers an excuse to write about subjects they would not previously have been allowed to cover: if there is a lively debate online about a case of local corruption, for example, official media can use this as a justification for reporting it
Indeed newspapers like the Guangzhou Daily now have whole pages devoted solely to stories from blogs and websites.
According to David Bandurski of the China Media Project at Hong Kong University, the relationship between media and the internet has created something of a virtuous circle
"There's a growing interchange between professional and web media," he says. "People break stories on the web, which are picked up by newspapers, and their stories are then put up on the web, generating more public opinion."
Many journalists have also taken advantage of the greater space available on the internet to publish more information about stories than they can report in their newspapers.
One reporter, for example, published regular blog updates about how police in the southern city of Kunming were putting pressure on a family they had wrongly accused of forcing its teenage daughters into prostitution.
Journalists have also used blogs to publish stories which have been rejected by their editors as too sensitive - and indeed to reveal the restrictions which censors have imposed on their reporting.
The birth of micro-bloggers
The growing use of micro-blogs has given this phenomenon a new boost over the past year.
Qian Gang, former editor of the Guangzhou-based Southern Weekend, one of China's bolder newspapers, now has an estimated 1.5 million people following his views on news and current events.
Micro-blogging by ordinary citizens is also having an impact: in a recent case in Jiangxi province, attempts by local officials to cover up news of a clash which left one man dead when he tried to resist the forced demolition of his home were foiled after they began sending out micro-blog messages via mobile phone.
The local party secretary and several of his colleagues ended up losing their jobs.
Greater access to information has also spurred some net users to do more than just write about social issues. Some bloggers have begun to intervene directly in news stories and events.
In one famous case last year, Wu Gan, a blogger from southern China, travelled to central Hubei province after reading about the case of a young woman arrested for murdering a local official.
Suspicious of the details provided, he managed to make contact with the woman and film her telling her version of events, which was that she had been defending herself against attempted rape.
His film, which he posted online, aroused much anger among internet users, and led to widespread media coverage. The woman, Deng Yujiao, was eventually freed by the courts.
The Chinese government has of course responded with a string of measures aimed at controlling the flow of information on the internet.
Domestic web portals, for example, are only supposed to carry news from official state media sources.
A number of major Western media websites, including the BBC's, were blocked for many years, though most were unblocked in the run-up to the Beijing Olympics in 2008. The Chinese language BBC website, however, was blocked again in December of the same year.
People using internet cafes must register with their ID cards, while bloggers must in theory also register their real names with websites.
"Cyber police" patrol the net looking for subversive content. The government has also employed people to respond anonymously to critical comments in chatrooms, and online forums are themselves supposed to monitor postings and delete anything too political.
A new internet liability law introduced earlier this year also increased pressure on websites by making them legally responsible for the information they published.
And software is also used to filter out any reference to certain sensitive topics, including, recently, the name of the Nobel Peace Prize winner Liu Xiaobo and the movement which he founded, Charter 08.
A number of other activists who have used the Internet, such as Tan Zuoren, who sought to collect and publicise the names of children who died in school buildings which collapsed during the Sichuan earthquake in 2008 (as a protest against alleged shoddy construction), have also been jailed.
And over the past few years, the authorities have intermittently blocked access to various Web 2.0 sites, most recently Facebook and Twitter.
By-passing the law
Yet despite all of this, social networking and micro-blogging continues on China's many domestic equivalents - while a small but growing number of web-savvy Chinese citizens are using proxies and VPN networks to evade restrictions on access to foreign websites.
And China's domestic web forums have tended to remain sources of often controversial information about social issues and problems.
And the growing confidence and influence of China's internet users, many of them young people who have grown up seeing the internet as their personal space, was highlighted last year when the government announced that it would require all new computers sold in the country to be fitted with software known as the Green Dam.
This was said to filter out pornographic and violent content. A highly critical backlash against the idea, both online and in the media, eventually led to the cancellation of the scheme.
And as David Bandurski of the China Media Project puts it, the authorities are often in a position of playing catch-up with changes on the internet. Their draconian measures are a response to "pushing by journalists and web users".
"They are seeking a control strategy for this unstoppable social change," he says, "but they can't roll it back completely."
Indeed China's leaders have in the past few years shown signs that they realise this.
They seek to appease anger over internet controls by assuring people that they are listening to online public opinion: a white paper issued in September stressed that the internet was now an important channel "for the Chinese government to get to know public opinion and amass the people's wisdom," and insisted that freedom of speech on the net was now protected by law.
While this may not always be implemented, many local governments in China have now begun soliciting and responding to comments made by internet users, and have in some cases set up dedicated departments to address their complaints and queries.
At the same time, government officials are increasingly being given training in how to use social networking and other web tools to interact with the public.
It is, says David Bandurski, an attempt to create a type of "online democracy" - one which the government may hope will allow people to let off steam, and thus alleviate pressure for other types of democracy within China's system.
The authorities may also have realised, of course, that the internet can also be a useful tool for promoting their own message - and, when required, for spreading patriotic or nationalistic sentiment.
In 2008 a campaign against Western media coverage of riots in Tibet and disruption of the Olympic torch relay by supporters of Tibetan independence led to the foundation of a website known as anti-CNN.com, which detailed alleged anti-China bias in Western media coverage, and rallied millions of young people to the government's cause.
Yet the fact that the internet has effectively replaced other channels of communication in China means that it is also open to distortion and rumour.
The phenomenon of the so-called "human search engine", in which large number of internet users pool resources to uncover the identities and backgrounds of people accused of misdemeanours, has led to the exposure of a number of cases of corruption.
But in some cases it also led to persecution of ordinary people over, for example, their private lives - sometimes based on incorrect information.
In this sense, the internet has sometimes become the nearest thing China has to a tabloid press.
Still, many believe that the internet has, overall, had a positive impact on Chinese society.
There can certainly be little doubt that its influence on society in China is arguably greater than in almost any other country - not least because of the lack of alternative sources of information.
And while official efforts to manage the internet are undoubtedly becoming increasingly sophisticated, few believe that the clock can be completely turned back.
Blogger Isaac Mao, whose micro-blogs have tens of thousands of followers in China, says that the sharing of what he calls "collective knowledge" has now become an important part of China's reality, making people less willing to blindly accept what they are told by the authorities.
"People want more information now," he says, "and they are using social networks to relay it from one group to another. It's getting harder for the censors to really stop the spread of information - personally I don't believe that censorship can go much further."
Duncan Hewitt is a former BBC China correspondent.