Here is an example of the new ExternalInterface class available within the Flash 8 player. It implements both JavaScript calling ActionScript functions and ActionScript calling a JavaScript function. (Local link, requires Flash 8 )  Read more...

Thanks to Tinic Uro, the principle engineer on the Flash Player, we have a hidden feature that can be used. Set both the base movie clip and the mask to make use of runtime bitmap caching, and alpha gradients will work!

View the example (Local to site, requires Flash Player 8 to view).

Example FLA. (Right click and “save link as…” to download)