This website showcases good deeds done by people who listen to police scanners. Info is listed by date of occurrence.
Best stories -
2016 - Saginaw Michigan - crime down 13% - murders down 38% - Police Chief praises scannerists
2015 - Braintree Massachusetts - scannerist busts burglar
2015 - Hermitage Tennessee - scannerist leads police to 2 armed robbers
2015 - Winchester Virginia - scannerists helps officer in trouble
2015 - Gresham Oregon - scannerist almost catches murderer
2015 - Tewksbury Massachusetts - scannerist leads police to attempted murderer - February 2015
2015 - South Dakota Attorney General wants to legalize scanners - January 2015
2014 - December - 2 Chicago scannerists save 2 people from a fire
2014 - Dec 10 - even fire departments from Australia are now providing official scanner feeds
2014 - Dec 1 - big story about scannerists from Beloit Wisconsin
2014 - Chicago Police sued for illegal use of Stingray to intercept cellphone calls - Broadcastify caught radio traffic
2014 - Scranton PA - bar owner / scannerist alerts police to robber sitting in the bar
Dec 2013 - scanner comforted family in basement during EF4 tornado in Washington Illinois
2014 - scannerists find San Diego County fire radio problem
2014 - scannerist provides Ferguson MO tape
2002 - news media with scanners helped get the DC Snipers
2006 - Tyler Texas - scannerist leads police to 2 guys who shot a cop
April 2013 - Watertown Mass - residents used scanners for situational awareness during search for bombers
Jan 2013 - capture of bank robber near Carson Nevada.
Feb 2014 - another bank robber busted - this time in Queens NYC.
April 2014 - shooter bagged by Wilkes Barre PA scannerist
Please also check out the ' sonofrcma ' or ' firerad2 ' lists at yahoogroups - you can use the keyword "openness" to find many more good scanner stories there
http://www.radiobanter.com/search.php?searchid=58897 - many openness posts here
https://sites.google.com/site/sonofrcma/ - Legalities of Scanning - Ethos of Scanning
http://forums.radioreference.com/virginia-radio-discussion-forum/191875-moral-dilema-2.html - Will online feeds kill the scanning hobby?
Odds and Ends
Kidnapper busted by scannerist - see the public comments - http://www.tulsaworld.com/news/article.aspx?subjectid=318&articleid=20120505_78_A15_BOEROe845115
There was a tow truck driver in Scranton PA IIRC (maybe Wilkes Barre Pennsylvania) that busted a couple of people during police chases - rammed them with his truck or held them at gun point - circa 2004 - (I think he is still at it in 2014)