Adobe APIs
corelib, mappr, flickr, youtube and more.
http://labs.adobe.com/wiki/index.php/ActionScript_3:resources:apis:libraries
APE (Actionscript Physics Engine)
http://www.cove.org/ape/
as3awss3lib
ActionScript 3.0 library for interacting with Amazon S3
http://code.google.com/p/as3awss3lib/
as3soundeditorlib
Actionscript 3.0 library for sound editing
http://code.google.com/p/as3soundeditorlib/
as3ds
AS3 Data Structures For Game Developers
http://code.google.com/p/as3ds/
ASCOLLADA
http://code.google.com/p/ascollada/
As3Crypto
ActionScript 3 Cryptography Library
http://crypto.hurlant.com/
asinmotion
Animation Library for AS3
http://code.google.com/p/asinmotion/
Away3d
http://code.google.com/p/away3d/
ebay API
http://code.google.com/p/as3ebaylib/
facebook-as3
AS3 API to access Facebook's Platform API
http://code.google.com/p/facebook-as3/
flest
Flest Framework for Adobe Flex and ActionScript3 Applications
http://code.google.com/p/flest/
FZip
Actionscript 3 class library to load standard ZIP archives and extract/decompress contained files.
http://codeazur.com.br/lab/fzip/
lastfm-as3
Actionscript 3.0 library to access the Last.fm web services
http://code.google.com/p/lastfm-as3/
MapQuest
http://company.mapquest.com/mqbs/4a.html
mecheye-as3-libraries
A set of ActionScript 3 Libraries, primarily for Flash game development.
http://code.google.com/p/mecheye-as3-libraries/
Papervision3D
http://code.google.com/p/papervision3d/
Salesforce Flex Toolkit
http://wiki.apexdevnet.com/index.php/Flex_Toolkit
Tweener
Full featured animation library
http://code.google.com/p/tweener/
Twitter AS3 API
http://twitter.com/blog/2006/10/twitter-api-for-flash-developers.html
uicomponents-as3
Lightweight AS3 UI component library
http://code.google.com/p/uicomponents-as3/
XIFF
XMPP client library
http://svn.igniterealtime.org/svn/repos/xiff/branches/xiff_as3_flexlib_beta1/
Yahoo AS3 APIs
http://developer.yahoo.com/flash/as3_api_libraries.html