Swift 3d is a great utility for creating flash animations (specially banners). You can use the stand alone program from erain or as a 3dmax plugin.You can make 3d animations in it (or it will look 3d anyway) and it brings flash animation creation closer to the way programs like 3ds max does things.The only down side it's that it's not free.

Poser is a nice utility for creating humans and animations. It can export in flash format.

http://www.flashkit.com/movies/ is a good resources for .fla files.
http://www.flashmo.com/ prove itself useful a bunch of times
A google search for cool flash effects might do the trick also

Search the web for sothink swf decompiler.
Or to find other decompilers you can just search for swf decompiler.

1pixelout.net made a great free mp3 flash player; they made it mainly as a wordpress plugin but it is very easy to implement it on it's own.

To implement it you only need 3 files:

audio-player.js
player.swf
an mp3 file

You can embed it like this:

how to create cool flash movies without coding flash?
How to create 3d models in flash?
How to create easy flash animation?A 3d application that exports in flash?
How to export 3d max in flash