Adobe used to have individual Cookbooks applications for Flex, AIR & Mobile that presented code snippets created by the community.

Now, they have combined all, with new additions, under a single Adobe Cookbooks application.

The website is a great place for finding ready-to-use code samples for Adobe products, specially ActionScript & Flex.

Besides adding new snippets, users can request for the ones that they can not find & other users can create/share them.

The new Adobe Cookbooks also offers a better search/browsing experience with titles like "related recipes" & "contributor lists".

CASA Lib (formerly CASA Framework) is a flexible ActionScript library for coding more reliable & faster.

It provides a core set of classes, interfaces, utilities & has AS2 – AS3 versions.

It standardizes the loading of external files with an easy-to-use and consistent API.

And, it has a powerul garbage collection with a common destroy(); method.

CASA Lib has lots of features that can "almost always" help in a Flash coding task.

The library is also well-documented with explanations/examples of every class & utility.

SwfVersion.com is a handy web service (free) that Flash developers will love.

It enables you to learn "for what version of Flash Player the SWF was published" & also the ActionScript version used.

You can upload a SWF file or mention the URL of it to get the results.

The service uses the SWFReader class which helps getting almost any information out of a SWF file.

Image Gallery is a free Flash image gallery that comes with the source code.

Settings are configured from a XML file like the names of the categories, images & folders where the images resides.

The gallery presents the images randomly or with an order (can be set via the XML file).

When a thumbnail is clicked, original image is presented in a Lightbox like Flash pop-up, images in that gallery can be browsed easily & even viewed as a slideshow.

The demo of the gallery can be viewed from here. As there is no direct link for the source file in the website, you can download it from here.

P.S. I have contacted Tony Yoo (owner of the gallery) & yes, it is free.

gTween is a lightweight (4.5kb) Flash tweening engine for AS3.

The engine is fast (1500 instances, 0.5s duration, ~25fps) & it is resource-friendly – consumes CPU carefully.

gTween has an attractive proxy tweening property that allows you to work with tween destination values the same way you would work with them on the target object.

Some features of gTween:

• Interrupting tweens
• Sequencing tweens
• Multiple timing modes
• Pause all
• Activate, init & complete events. And, custom progress points
• Auto-hide, auto-reverse, smart-rotate & more..

Update: This resource seems to be unavailable from now on.

This is a free streaming Flash MP3 player that is easy to use & customize as it comes with the .FLA file.

The player uses a XML file where its design can be customized and the song to be played can be mentioned.

The player plays 1 song which makes it ideal for using it as a website background music player or can be improved further.

It is written with Flash8 / AS2.

Sandy is an open source & user friendly 3D engine for Flash (AS2 & AS3).

This 3D Flash library is able to render about 2000-5000 polygons correctly on a pretty recent computer with really correct screen resolution.

Some features of Sandy:

• Viewing volume clipping for perfect rendering
• Advanced shading effects.
• Material system to easily change your objects appearance.
• Advanced and easy object management.
• Advanced camera management.
• Complex object loading thanks to the .ASE and .WRL files parser , but also Collada and 3DS files for AS3.
• Flash player 7 to 9 compatibility.
• Both MTASC and Macromedia compilers compliant for AS2 and Flash CS3 and FlexBuilder for AS3 versions.
• Several 3D primitives.

Flare is an ActionScript library for visualizing data like creating charts, graphs and complex interactive graphics.

The library supports data management, visual encoding, animation, and interaction techniques. It provides a modular design which enables you to create customized techniques easier.

Flare has a tutorial which will help you to start using it and its API is well documented.

To see its power, check the demos.

ToobPlayer is a lightweight (approx. 14-8 KB) FLV player component that comes in 5 flavors, provides a mechanism to play back YouTube videos, and can also display preview images.

Some features of this FLV player:

• Resizable, optional full-screen mode
• Several video resize mods
• Loading status feedback
• Mouse wheel support (seeking & volume)
• Auto-repeat, buffer time
• Customizable
• Extensive API

ToobPlayer YouTube integration is done with a simple PHP proxy script to automate acquaring  videos & images.

The component requires Flash Player 8+ & AS2.

TweenLite is a lightweight and fast tweening engine for Flash AS2 & AS3.

It is lightweight because it only takes 3kb when published which makes it one of the smallest tweening engines around. And you can extend it with TweenFilterLite and TweenMax to add ColorMatrixFilter effects like saturation, contrast, brightness, hue, and even colorization.

Why use TweenLite rather than built-in tweening engine?

• SPEED. TweenLite is much faster.
• onComplete, onStart, onUpdate callbacks (plus the ability to pass any number of variables to them)
• autoAlpha (toggles visibility of an object off when the alpha hits zero)
• Tween multiple properties with a single call
• Delay any tween by a set amount (good for sequencing)
• Tween the tint of any MovieClip/Sprite VERY easily
• Tween the volume of any MovieClip
• more..

Usage of TweenLite is very simple:

TweenLite.to(target:Object, duration:Number, variables:Object);

is the most basic usage. You can add more variables that can be found at the product page.