Grant Skinner created a more lightweight class named GTweeny based on the original GTween class. The new class is under 3Kb and Grant Skinner is looking for feedback about it. There’s a cool image gallery developed using this class and it is a good example how this class can be useful for you.

webresourcesdepot.com has posted 10 actionscript libraries / classes which are not so famous has Papervision, Flare and others.

These are also very useful and you will for sure enjoy to meet some of them.

The list includes:

Playr (AS3 music player class)
flXHR (Flash solution that mimics Ajax by a XMLHttpRequest compatible interface)
KitchenSync (focused on sequencing animations and other time-based actions)
AnimationPackage (AS3 library for creating powerful, maintainable animations and primitive shapes)
Flint (Flash library for creating particle based effects)
AsWing (making Flash application UIs easily)
ActionScript Page Flip Class (create the famous page flip effect)
ASZip (zipping with Flash)
FZip (loading, modifying and creating standard ZIP archives)
AS3Crypto (cryptography library that supports common algorithms like AES, DES, MD5 & more)