Este es el codigo full, te sirbe para yahoo e icq:
<html>
<head>
<title> Mensajeros </title>
<script language="JavaScript">
<!--
function mostrar(){
newwin = window.open('','','top=150,left=150,width=100,heig ht=100');
newwin.opener = self;
with (newwin.document){
open();
write('<html><body>');
write('<center> <b>Usuario</b> '+ usu.value);
if (chat.selectedIndex == 0)
write('<img border=0 src="http://opi.yahoo.com/online?u=' + usu.value + '&m=g&t=1">');
else
write('<img border=0 src="http://online.mirabilis.com/scripts/online.dll?icq=' + usu.value + '&img=2">');
write('</center></body></html>');
close();
}
}
//-->
</script>
</head>
<body>
<select name="chat">
<option value="yahoo">Yahoo
<option value="icq">ICQ
</select>
<input type="text" name="usu">
<input type="button" onClick="mostrar();" value="Estado">
</body>
</html>
Saludos espero te sirva
