How to create sub-nav when using a structured navigation heirarchy?
There is an nice recipe on the craftcookbook.net site from sprocketeer that explains exactly this.

{% set topEntry = craft.entries.depth(1).slug('information').first() %}
&lt;ul&gt;
    {% nav subEntry in topEntry.getDescendants() %}
        &lt;li&gt;{{ subEntry.title }}
            {% ifchildren %}&lt;ul&gt;{% children %}&lt;/ul&gt;{% endifchildren %}
        &lt;/li&gt;
    {% endnav %}
&lt;/ul&gt;﻿