http://www.gaiaflashframework.com/
Gaia is an open-source front-end Flash Framework for AS3 and AS2 designed to dramatically reduce development time.
Gaia is targeted at anyone who develops Flash sites. It provides solutions to the challenges and repeated tasks we all face with front-end Flash site development, such as navigation, transitions, preloading, asset management, site structure, deep linking and SEO, all without getting in your way. It provides speed and flexibility in your workflow and a simple API that gives you access to its powerful features.
Gaia enables you to develop feature-rich websites with significantly less code, and comes with built-in best practices including seamless integration with SWFObject and SWFAddress.
Most Flash frameworks are back-end frameworks, or require senior level coding experience to use. Gaia stands out because it focuses on front-end development. It is easy enough for novice Flash developers, yet powerful enough that advanced coders can use it without feeling limited.
Gaia uses a pragmatic and agile approach, and is focused on helping you do your job without getting in your way. And, it is flexible enough to enable you to work the way you like to work without forcing you to change your style.
Gaia’s author, Steven Sacks, narrates and demonstrates getting started with the Gaia Framework.
The latest version of Gaia can be found here.
The Gaia documentation is a robust Wiki, complete with code samples and lessons.
The Gaia documentation also has ASDocs for the AS3 version
Gaia has an active community of developers and designers, and the author is on the forums throughout the day.