fscommand()

fscommand() is a powerful Flash function that lets you call JavaScript functions and pass messages to Macromedia Director or Visual Basic, Visual C++, and the like.

I never use it, honestly. I have trouble making it work in Firefox (the Mozilla open source browser), though it works fine in Internet Explorer. I know most of the globe is on IE, but it's a principle thing for me. I want my Web sites to work on non-Microsoft browsers.