Q:

Output all categories down to the third level in the template

How can I retrieve the main categories and all subcategories three levels deep and display it in the template?

A:

<div class="left_content">
 <div class="menu">
    <?php $_helper = Mage::helper('catalog/category') ?>
    <?php $_categories = $_helper->getStoreCategories() ?>
    <?php $currentCategory = Mage::registry('current_category') ?>
    <?php if (count($_categories) > 0): ?>
            <ul id="menu">
            <?php foreach($_categories as $_category): ?>
                    <li class="sub">
                    <a href="<?php echo $_helper->getCategoryUrl($_category) ?>"><?php echo $_category->getName() ?></a>
                    <?php $_category = Mage::getModel('catalog/category')->load($_category->getId()) ?>
                    <?php $_subcategories = $_category->getChildrenCategories() ?>
                    <?php if (count($_subcategories) > 0): ?>
                        <ul>
                         <?php foreach($_subcategories as $_subcategory): ?>
                            <li>
                                <a href="<?php echo $_helper->getCategoryUrl($_subcategory) ?>">
                                <?php echo $_subcategory->getName() ?>
                                <!--sub sub category-->
                                <?php $_subcategory = Mage::getModel('catalog/category')->load($_subcategory->getId()) ?>
                                <?php $_subsubcategories = $_subcategory->getChildrenCategories() ?>
                                <?php if (count($_subsubcategories) > 0): ?>
                                 <ul>
                                 <?php foreach($_subsubcategories as $_subsubcategory): ?>
                                 <li>
                                    <a href="<?php echo $_helper->getCategoryUrl($_subsubcategory) ?>">
                                 <?php echo $_subsubcategory->getName() ?>
                                    </a>
                                 </li>
                          <?php endforeach; ?>
                        </ul>
                     <?php endif; ?>
                                 <!--sub sub category-->
                                </a>
                            </li>
                        <?php endforeach; ?>
                        </ul>
                    <?php endif; ?>
                    </li>
             <?php endforeach; ?>
            </ul>
    <?php endif; ?>
    </div>

</div>

