Getting Next Tag In List, NextSibling Gives Unexpected Results

Considering the following list how do I get a reference to the ul just below
the li with id products? nextSibling gives me a reference to the #text# node
inside the li tag?

<ul>
<li id="products">products</li>
<ul>
<li id="child">child</li>
<li id="chair">chair</li>
</ul>
</ul>

I want to create several functions to add or remove items from the list.