I used to do quite a bit of Flash programming, but it's been a while since I've used Flash. I'm mostly using HTML5/Canvas and Processing.js these days. I started a tutorial blog over at Joy of Processing.
In 2003 I started teaching myself Flash actionscript and made a number of amusing software toys in Flash. Many of the programs I had originally written in Java, such as the tasteless Charles Manson Tamagotchi, I ported to Flash. The flash equivalents of these java programs have better performance and load much faster.
I used to teach an actionscript programming class to high school kids in the Los Angeles area.
Looking for a book on Flash Actionscript? There are a lot of Flash books out there, and most of them are not that great in the actionscript department. Here's a list I've put together of the few that I like.
These non-flash books are also quite useful: