function aleatoire(N) {
		return (Math.floor((N)*Math.random()+1));
	}

var adr_dest = ["0",
		"<iframe src='http://www.gratuit-xxx.com/images/catch-gene/formulaire.html' framespacing='0' frameborder='no' scrolling='no' width='923' height='110' allowtransparency='true'></iframe>",
		"<iframe width='915' height='115' src='http://media.acces-charme.com/email_catcher/track.php?idw=45&idcatcher=407&format=915x115&typef=design&lg=fr&idn=&t1=gratuitxxx&t2=haut&rebill=0' scrolling='no' frameborder='0' style='margin:0; padding:0' allowtransparency='true'></iframe>"];

    adr1=aleatoire(2)
    					
		document.write(adr_dest[adr1]);