Flash
Although not formally taught Flash or ActionScript, I have found that the latest version of ActionScript (AS3) very agreable in both functionality and extensibility. Below is a running list of assets I utilize during my projects.
Flash Utilities:
TweenLite – website
SWFObject – website
SWFAddress – website
Google Analytics – website
Papervision 3D – website
Away 3d – website
Flint Particle System – website