The parent categories plugin allows you to have a list of all your parent categories for use in a sidebar or a list.
To call this function you would include the following code in any template file you want it to appear.
{categories_parent}
<ul>
{foreach from=$pcat item=entry}
<li>{$entry.link} {$entry.total}</li>
{/foreach}
</ul>
The code above calls a Smarty custom plugin that we have created. The file is located at plugins/function.categories_parent.php