What are friendly URLs? 

The idea is instead of something like this in the address bar:

http://www.yourunfriendlysite.com/index.cfm?event=someAction

you have something a) perhaps more easily remembered, and b) easier on the eyes like this:

http://www.yourfriendlysite.com/someAction/

Pete Frietag has written a great example of how to use friendly urls in your application. Expecially for those of us that use frameworks such as Mach-ii, Fusebox, Model Glue, etc., this is a nice touch to add to an application.