Use Javascript from Actionscript
I use this trick all the time to communicate between Flash and the Browser, especially since it's cross-plattform and cross-browser compatible. I just read about it in a blog and figured that not everyone might know this, so if you find yourself from time to time in a situation where you'd need to call Javascript-Functions from Flash (like for example to change someting in the DOM model) head over to Kevin Lynch and read his informative post: Use Javascript from Actionscript