Here are some useful links to get started with AS 3:

From www.helpqlodhelp.com:

• Actionscript 3 – First Steps
• Actionscript 3 – First Steps II
• Actionscript 3 – First Steps III
• Actionscript 3 – First Steps IV
• Actionscript 3 – First Steps V
• Actionscript 3 – First Steps VI
• Actionscript 3 – First Steps VII
• Actionscript 3 – First Steps VIII
• Actionscript 3 – First Steps IX
• Actionscript 3 – First Steps X
  
• Actionscript 3 – First Steps XI
• Actionscript 3 – First Steps XII
• Actionscript 3 – First Steps XIII
• Actionscript 3 – First Steps XIV
  
• Actionscript 3 – First Steps XV

Tutorials from by Betaruce:

• Basic tutorials for AS3 with focus on the Flash 9 alpha preview

Flashguru posts:

• Loading external Resources (Bitmaps) with AS3 here.

Senocular:

• Using AS3 with the free Flex SDK here.

GoToAndPlay() Tutorials:

• Getting started with Actionscript 3
  

assertTrue:

• AS3 only projects with Flexbuilder

to be continued…