So, I'm playing with Flixel, which is making Flash games actually fun to work on. Here's what I've gotten done in an afternoon of fiddling with the included documentation and poking through the example source code (after the jump). Already it's a hundred times faster and cleaner than the vertical-shooter engine I wrote for Flash MX back in high school, and I've hardly done anything yet!
Flixel is making it particularly easy to slide back into ActionScript and get some simple game mechanics up and running, though. Too many game engines try to remove coding from the process of game development; Flixel, by contrast, makes coding easy and sensible. Adam's extensions to Flash's Sprite class for FlxSprite make a lot of sense for on-screen game objects, and using a state manager to handle the game loop is so simple it had to be designed.
What I'd like to do next is see Game Programming Patterns expanded to handle some basic event loop / screen object hierarchies.