Having freelanced for over 18 months now I find it interesting to see how different companies work and the tools their development teams use. Here is a quick insight into some of the tools I use in my everyday Flash development work. These views are in no way advisory but offer an insight into the tools I use most often and most helpful in my work flow.
Flash CS5 - Info
For any reasonable project Flash is always going to be necessary whether it be setting up animations or allowing layouts to be easily amended by a designer. I used to run CS4 but found out that some agencies are quick to use the latest software as it is released. Being a freelancer it help that I am able to fit into any team situation so the latest software is a handy when using my own setup, to save bothering the team to back save any files for me.
Flash Builder 4.5 - Info
With all the recent advances by the Adobe team in relation to mobile I enjoy the capability to be able to try stuff out as soon as it is released. Now this isn't to say this can't be done with other code editors (e.g. Flash Develop, FDT etc) but I like the way that my license fee keeps me up to date on the IDE and any changes that may come. The profiler is great when it comes to testing memory management.
Robotlegs AS3 - Download
This framework has been around for a while now and many of the big agencies are using Robotlegs as their framework of choice for the ease at which it can be implemented and extended. This is not to say I use Robotlegs in all projects - each project calls for it's own analysis, I just like the way it works and coupled with AS3 Signals creates an easily interpretable code base.
Gaia Framework - Download
This is one little framework which I feel sometimes slightly get looked down on. Many of us started out in Flash development building small micro-sites. In this scenario I feel this to be the best framework to get you up and running, with inbuilt deeplinking and transition control, it's possible to get an overall site structure up and running within 15 minutes. The reason I say that this is sometimes looked down upon is due to the way people feel they should be using the latest frameworks such as Robotlegs and PureMVC. At the end of the day it's all about finding the best framework for the job and I personally feel Gaia is up there. I also like to do the right click check (Gaia sites by default display a created using Gaia entry) on many popular sites and even recently I found some of the biggest agencies we all know to make clear use of Gaia.
BulkLoader - Download
With any major flash project it is inevitable that you will need to load in a number of assets. BulkLoader allows me to throw in assets as I need them and pull them out in the same fashion, nothing overly complex but being open source makes it a user tried and tested library.
Greensock Tween Library - Download
There are many tween libraries around, more through expanse of use than anything else this is the one I add to my project templates. It's minimal overload and allows me to run a number of different tweens besides the usual object properties, including delayed calls and path tweens.
AS3 Signals - Download
More of something I like to use than something I use regularly. It means I don't have to extend the flash.events.EventDispatcher class and accepts any number of arguments I pass into it. This works great with Robotlegs when used with the Signal Command Map and makes for a framework that is easy for me to explain to other members of the team who may not be familiar with the MVC design pattern.
Sound Management - Sound Manager v1.4 - Download
I recently discovered Sound Manager and so far it has helped me out a great deal. There's still room for development in the library but when used within a singleton it allows you to easily manage all of your sound assets in one place. You are able to control global volume settings and trigger sounds as they are required.
Hopefully this give an idea to a few guys who wonder what kind of libraries and setup I use within my freelancing roles.