If we were making an app guide for Nancy Grace, 5-0 Radio Pro would be our top pick. It lets you listen to more than 35,000 live police and fire department radio feeds from around the world. Check your city's channels for breaking news, or pick one from the Top 100 guide just for kicks.
WIRED Includes definitions of common police codes in each city. You can record the juicy bits as MP3s.
TIRED Feeds are organized by county — tedious for browsing.