You could probably use the book module combined with <a href="http://drupal.org/project/menu_block">http://drupal.org/project/menu_block</a> to achieve this. The sub items are a nested list. It will give you something like this <a href="http://pastebin.com/3XNGT1QK">http://pastebin.com/3XNGT1QK</a><br clear="all">
<div><br></div><font color="#333333">Carl Wiedemann</font><div><div><font color="#333333">Website design &amp; development consulting</font></div><div><font color="#333333"><a href="mailto:carl.wiedemann@gmail.com" target="_blank">carl.wiedemann@gmail.com</a> | skype: c4rlww</font></div>
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<br><br><div class="gmail_quote">On Thu, Feb 23, 2012 at 7:33 AM, <a href="mailto:correogracioso@yahoo.es">correogracioso@yahoo.es</a> <span dir="ltr">&lt;<a href="mailto:correogracioso@yahoo.es">correogracioso@yahoo.es</a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="color:#000;background-color:#fff;font-family:times new roman,new york,times,serif;font-size:14pt"><div>

    <div>I show you my menu in my home:<br><a href="http://groups.drupal.org/files/menu_0.png" rel="nofollow" target="_blank">Menu</a></div>
<div><a href="http://groups.drupal.org/files/menu_0.png" target="_blank">http://groups.drupal.org/files/menu_0.png</a><br></div><div>And this is what i need when people click in &lt;&lt;&#39;musical 
services&#39;&gt;&gt;, isn&#39;t a hover or on:click. I mean, when 
musical-services page loads, it loads the submenu too.<br><a href="http://groups.drupal.org/files/submenu.png" rel="nofollow" target="_blank">submenu</a></div>
<div><a href="http://groups.drupal.org/files/submenu.png" target="_blank">http://groups.drupal.org/files/submenu.png</a><br></div><div>How do i do this, any tutorial or something?</div>
<div>Thank you, Jorge.</div>
  </div><div> </div><div><div><hr style="width:100%;min-height:2px"><font color="#FF0000" face="courier, monaco, monospace, sans-serif"><b><u>Jorge</u></b></font><a rel="nofollow"><font color="#ff0000" face="arial black"><b></b></font></a></div>
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