Missing children are to be sought via the error pages websites display when people reach deleted webpages.
A European initiative is putting pictures and biographical details of missing children on the well-known 404 Not Found pages.
Hosting firms, ISPs and media companies have signed up to put the information on what would otherwise be empty pages.
Anyone who runs a website is being encouraged to join the initiative to raise the profile of missing children.
Snippet of code
The NotFound project has been created by Missing Children Europe, Child Focus, the European Federation for Missing and Sexually Exploited Children and several other European organisations.
While there are standard ways of setting up a 404 Not Found page, increasing numbers of websites are customising the error page to redirect web users who go astray or who visit an old page.
NotFound wants sites to add a snippet of code to those customised pages so they display data about missing youngsters.
So far, about 480 sites have signed up to the NotFound initiative and reconfigured their 404 page to help.
Maryse Roland, a spokeswoman for Child Focus, said a random process governed which missing child would be highlighted.
"It could be a recent disappearance, or on the contrary, a child that has been missing for a long time," she said.
"This project will allow us to once again concentrate the attention on children whom we haven't heard of for many years," said Ms Roland. "These children risk falling into oblivion."
Once sites have signed up and added the code supplied by the NotFound project, every time the page is displayed it will contain information about a missing child.
Francis Herbert, secretary general of Missing Children Europe, said: "We are always looking for new communication channels to distribute missing children messages and increase the chances to bring them home."