A common thing requested by clients is special behaviors when a swf is running on a particular site. Here’s a simple test for what domain your SWF is currently playing on:

        public function isPlayingAtDomain( a_domain : String ) : Boolean
        {
            var url : String = this.stage.root.loaderInfo.url;

            var urlStart : int = url.indexOf( "://" ) + 3;
            var urlEnd : int = url.indexOf( "/", urlStart );
            var domain : String = url.substring( urlStart, urlEnd );
            var lastDot : int = domain.lastIndexOf( "." ) - 1;
            var firstDot : int = domain.lastIndexOf( ".", lastDot ) + 1;
            domain = domain.substring( firstDot, domain.length );

            return domain == a_domain;
        }