var azar = parseInt((Math.round((Math.random() * 2))));;
url_htmls = new Array();
url_img = new Array();

url_htmls[0] = 'http://muyamateur.com/webcams-amateur/';
url_htmls[1] = 'http://muyamateur.com/webcams-amateur/';
url_htmls[2] = 'http://muyamateur.com/webcams-amateur/';

url_img[0] = 'http://descargas2.tuvideogratis.com/muyamateur/banners3/728x90_01.gif';
url_img[1] = 'http://descargas2.tuvideogratis.com/muyamateur/banners3/728x90_02.gif';
url_img[2] = 'http://descargas2.tuvideogratis.com/muyamateur/banners3/728x90_03.jpg';

var banner = '';
banner += '<' + 'a href="' + url_htmls[azar] + '" target="_blank"><' + 'img src="' + url_img[azar] + '" ';
banner += ' width="728" height="90" border="0"><' + '/a>'; 

document.write(banner);