menu { main_id, sub_id, title, link }
0,0,'About This Site','about.php';
0,1,'Website Features','features.php';
0,2,'Partners','partners.php';
...etc...
since you know css, i'm sure you know how to do the hidding of menus etc. so just build it from there... to create the main menu, do something like:
$q1 = mysql_query("select from menu where sub_id = '0' ");
while($r1 = mysql_fetch_array($q1)){
echo $r1['title'];
$current = $r1['main_id'];
$q2 = mysql_query("select from menu where main_id = '$current' and sub_id not like('0') ");
while($r2 = mysql_fetch_array($q2)){
echo $r2['title'];
}
}
that's the basic jist of it... you will obviously have a lot more work to do with it, but that should help you create a backbone for it. good luck.