Most useful ActionScript packages / libraries

Common libraries:

http://casalib.org/
http://code.google.com/p/as3corelib/

Physics Engines:

http://box2dflash.sourceforge.net/
http://www.cove.org/ape/

Flash 3D engines:

http://away3d.com/
http://papervision3d.org/
http://alternativaplatform.com/en/
http://www.flashsandy.org/

Tweening:

http://greensock.com/gsap-as/
http://www.gskinner.com/libraries/gtween/

Graph/Chart + Particles:

http://flare.prefuse.org/demo/

Chart:

http://pullmonkey.com/projects/open_flash_chart

Particles:

http://flintparticles.org/

Game Engine:

https://code.google.com/p/pushbuttonengine/

Augmented Reality:

http://www.libspark.org/wiki/saqoosha/FLARToolKit/en

A clear, lightweight and performant data structures / collections library:

AS3Commons Collections

Layout framework:

AS3Commons UI - Layouts

A standard UI component library including with focus on customization, data intergration and performance. Including TreeView, ListView, SelectBox, ColorPicker, etc ...

AS Data Provider Controls

http://www.unionplatform.com

A client/server framework for creating multiuser applications and multiplayer games.

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asMock : Dynamic mocking framework for AS3 with integration support for FlexUnit 1/4.0/4.1, ASUnit and fluint

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