Adobe Flex 3 Live Doc

http://livedocs.adobe.com/flex/3/html/

Adobe Flex 3 Getting Started
http://learn.adobe.com/wiki/display/Flex/Getting+Started

Source Code:
http://learn.adobe.com/wiki/display/Flex/Download+Projects

Get oriented to Flex
1. Creating a Simple RIA
2. Exchanging Data
3. Top things you need to know
   a. Working with Data
   b. Handling Events
   c. Designing a UI - Layout
   d. Displaying lists of items
   e. Multi-page applications
   f. Customizing components
   g. Debug your application
4. Building Your Own Flex Application

Flex Related Open Source Project
http://opensource.adobe.com/wiki/display/site/Projects
-BlazeDS
-Cairngorm
-FlexUnit
-Generic Image Library
-Open Source Media Framework