What are good books / site where you can learn the best practices for event driven programming in actionscript (3 obviously).
I've got a big project coming up and, to be honest, my flash is usually a big mess of classes and I don't want the the next one to turn into a ball of hair behemoth.
After buying ActionScript books I still use the Adobe PDF Manuals the most. They are free downloads:
From this site: http://www.adobe.com/support/documentation/en/flash/ you can get just about every Flash and ActionScript reference for Free, including:
Flash Tutorial: http://livedocs.adobe.com/flash/9.0/UsingFlash/flash_cs3_help.pdf
Programming Action Script: http://livedocs.adobe.com/flash/9.0/main/flash_as3_programming.pdf
Language and Component Ref Zip: http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3.zip
Colin Moock's Essential Actionscript 3.0 has a good explanation of events.
If you want free online stuff, here are some introductory articles on how AS3 Events work with the Display list:
Using Event Dispatcher is for AS2/Flash MX 2004, but is a decent introduction to the concepts of events, event dispatchers, and event listeners.