London's Metropolitan Police have produced an app called Facewatch ID that is billed as a crowdsourcing tool for identifying suspects shown in stills from CCTV footage of last summer's riots. But the 2,800 riot images also include "a further 2,000 images of people wanted by the police for offences not connected to the riots." From the BBC:
Assistant commissioner Mark Rowley, head of specialist crime and operations at Scotland Yard, said: "This is a great opportunity for the public to help us fight crime and bring those who remain outstanding to justice.
"My hope is that the two-thirds of Londoners who own smartphones will download this app, and help us identify people we still need to speak to.
"We need Londoners to browse through the app every week or so as new images will appear regularly. This is a fantastic way for Londoners to help us to fight crime."