podrias armar un pop up que salte en el onLoad de tu site.
Pone lo siguiente:
Código HTML:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script language="JavaScript">
function homePopup()
{
ancho = 447;
alto = 215;
y = screen.height/2 - alto/2;
x = screen.width/2 - ancho/2;
window.open("atencion.html", "w", "width="+ancho+",height="+alto+",left="+x+",top="+y+",status=no,scrollbars=no");
}
</script>
</head>
<body onLoad="homePopup();">
</body>
</html> 