I'm excited to see the Adobe Developer Center has put up the "Object-Oriented Programming with ActionScript 3.0" article I wrote for them a little while back. The article runs through the basics of inheritance, encapsulation and polymorphism and is aimed at those of you that haven't made the step to class-based development yet. While the examples use Flash as an authoring environment, these concepts can just as easily be used when doing doing development in Flex Builder.
If you enjoyed the read and want a more indepth look at OOP with ActionScript 3.0, there's the book coming out this summer that should help you along.
Its always great working with the developer center team so thanks to Stefan, George et al. for their hard work editing the article and putting up with me ;)