Shneiderman said the site could put a digital spin on the American tradition of neighbors helping neighbors. For example, he noted that 7 million people have registered to receive "Amber Alerts," notices to citizens about what or who to be on the look out for when a child goes missing.

"There are certain members of the community who care about issues and are ready to get involved when things are happening," Shneiderman said. "There is also good evidence that shows ... that these kind of electronic networks can generate local action and local engagement that continues offline."

Shneiderman, who has asked the National Science Foundation for money to test the 911.gov concept on the University of Maryland campus, noted that such a project would have obstacles, such as warding off hoaxes and building an environment of trust where people would ask for and offer assistance to one another.