How can I display a view's count in a navigation item?
I know only how to get it with codding.
You can define in your module function, which gets total rows count from your view. And you can use drupal cache system for result, but actually you can use Views cache for it.
Something like that:


/**
 * Executes View to know rows count
 */
function testm_get_view_items_count($view_name, $display_id, $args) {
    $count = &amp;drupal_static(__FUNCTION__);
    if(!isset($count)) {
        if($view = views_get_view($view_name)) {
            $view-&gt;set_arguments($args);
            $view-&gt;get_total_rows = true;
            $view-&gt;execute($display_id);
            if(isset($view-&gt;total_rows)) {
                $count = $view-&gt;total_rows;
            }
        }
    }
    return $count;
}


You can add cache_set/cache_get as Lulabots showed, but then you need to think about when to do flushing you cache.
You can use this function in THEMEORMODULE_preprocess_menu_link() function in Drupal 7. Here I showed example.
This code works on D7.