esto esta hecho en un estilo FORM
<html>
<head>
<title>mi titulo va aqui :)</title>
<HEAD>
<SCRIPT LANGUAGE="JavaScript">
<!-- Begin
function formHandler(form){
var URL = document.form.site.options[document.form.site.selectedIndex].value;
window.location.href = URL;
}
// End -->
</SCRIPT>
</HEAD>
<BODY>
<center>
<table border="0">
<tr><th>Sitios</th></tr>
<tr><td>
<form name="form">
<select name="site" size=1>
<option selected>--Elegír una sección--</option>
<option value="http://www.yahoo.com">Yahoo
<option value="http://www.metacrawler.com">Metacrawler
<option value="http://www.altavista.digital.com">Altavista
<option value="http://www.webcrawler.com">Webcrawler
<option value="http://www.lycos.com">Lycos
<option value="http://javascript.internet.com">JavaScript Source
</select>
<br>
<center>
<input type=button value="visitar" onClick="javascript:formHandler(this)">
</center>
</form>
</td></tr>
</table>
</center>
</body>
</html>
Saludos
