Not sure if this has ever been posted but this is pretty neat, you can listen to Police, Sheriff and EMS all over the United States. www.radioreference.com/
The scanners are cool, and also you can get this kinda thing on your smart phone as well if you have one. It's only really interesting (at least to me) to listen in on the big cities, like Chicago or L.A. or the really crime ridden ones like Detroit. Otherwise there's really just a whole lot of nothing. But still potentially a good tool to use if something crazy breaks out.