Bakersfield pothole map
Locals report seeing potholes and they get mapped.
U.S. Fatalities in Iraq
Someone has taken the home of record for each U.S. fatality in Iraq and mapped it.
Chicago Crime Map
This one says down at the bottom: "Important disclaimer: This site is not affiliated with the Chicago Police Department. This site uses crime data obtained from the CPD's Citizen ICAM Web site, which is a publicly available database of reported crime. Please read the Citizen ICAM disclaimer to understand the data fully."
Bakersfield homicide map
"This is a map of Homicides in the Bakersfield area that occured in 2006. Locations are approximated and based on data provided by the Office of the Coroner."
In all these cases the data are mapped by someone who is not an official data producer, and at least in the pothole map case, the actual data are produced by individual citizens.
I don't take any credit for the above list of sites; it was compiled during the panel by the audience, participating in a chat room provided by the conference. So we have here a participatory journalism list of participatory journalism projects.
Here's a blog about the subject: Newassignment.net. Dan told an anecdote about when the U.S. House changed its rules to say that a speaker didn't have to resign if indicted. Multiple citizens called in to their representative's offices asking how their rep. voted. Apparently the representatives noticed something going on; in any case, the House then changed the rules back. This may be a case of simply using distributed participatory journalism to examine a situation caused it to change.
None of these examples would have been readily possible without the Internet. All involve participation, not centralized broadcast content.
I think it's good risk management for people to be able to see what's going on. Obviously some corporate executives, government administrators, and legislators may not agree, but that why it's good risk management for everyone else.
Various panelists did point out that reporting snippets to collate into a map doesn't make someone a professional journalist. Following up hard stories over a long time is a different kettle of fish, which few people have the skills and persistence to accomplish.