I know a lot of people have scanners and have them programmed into the "hot" frequencies in your neighborhood/community. But, if you do not have one, or don't know if you have the correct frequencies programmed, there is a website that will help you out. But, the main reason for this post is to help anyone monitor a scanner in an emergency or when there is a high profile incident going on and you want to keep up on the action.
I am going to post a link to a website, RadioReference, that has tons of scanner info. The page the link will take you to is the live scanner page. Let's say there is an emergency going on and you would like to monitor, but have no scanner. On this page you click the state where the emergency is (Say you live in Georgia but have a child going to school in Wisconsin, you would click on Wisconsin.) Then, click on the county where the emergency is taking place. You will get a list of scanners to monitor. Click on the one that seems to cover the area of interest. You wouldn't want to monitor aircraft/railroads if there was a major fire or hostage situation. Click on a good link and just listen. Just like you were there. You can also monitor in your own area as well, providing there is a scanner owner that is uplinked to the site. This is a pretty handy source of information.
Live Police, Fire, EMS, Aircraft, and Rail Scanners on RadioReference.com