Custom Magento Category Navigation

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<div class="category-navigation">
<?php

	// get the root category id
	$root_cat_id = Mage::app()->getStore()->getRootCategoryId();

	// get the current category object and ID
	$current_cat_obj = Mage::registry('current_category');
	$current_cat_id = $current_cat_obj->getId();

	// get the ID of the parent category from the current category
	$parent_cat_id = $current_cat_obj->getParentCategory()->getId();
	$parent_cat_obj = Mage::getModel('catalog/category')->load($parent_cat_id);

	// get the sub categories of the current category
	$sub_cat_obj = $current_cat_obj->getChildrenCategories();

	if($current_cat_obj->hasChildren()){
		// if the current category obj has children, use that
		$menu_cats = $current_cat_obj->getChildrenCategories();
		$menu_top_level = $current_cat_obj;
	}else{
		// else use the parent object
		$menu_cats = $parent_cat_obj->getChildrenCategories();
		$menu_top_level = $parent_cat_obj;
	}   

	// top level details
	$top_level_name = $menu_top_level->getName();
	$top_level_url = $menu_top_level->getUrl();
	$top_level_id	= $menu_top_level->getId();

	// is the top level the root?
	if($top_level_id == $root_cat_id){
		echo '<ul><li class="current">'.$current_cat_obj->getName().'</li></ul>';
	}
	else{

		// start navigation
		echo '<ul>';

		// check if the top level is the current category and output accordingly
		if($current_cat_id == $top_level_id){
			echo '<li class="current">View All</li>';
		}
		else{
			echo '<li><a href="'.$top_level_url.'">View All</a></li>';
		}

		// loop over all the sub category objects
		foreach($menu_cats as $key => $sub_cat){

			$cat_link = $sub_cat->getUrl();
			$cat_name = $sub_cat->getName();
			$cat_id = $sub_cat->getId();

			// check if the sub category is the current category and output accordingly
			if($current_cat_id == $cat_id){
				echo '<li class="current">'.$cat_name.'</li>';
			}   
			else{
				echo '<li><a href="'.$cat_link.'">'.$cat_name.'</a></li>';
			}

		}   

		// end navigation
		echo '</ul>';

	}   

?>  
</div>

<block type="core/template" name="superwickedcustomnav" template="page/custom-cat-nav.phtml" before="cart_sidebar" />

Use the XML snippet above in the left reference of catalog.xml to make the custom template appear in the left sidebar of all category and product pages.