How to add home page link in magento top menu?

Edit "app/design/frontend/<your theme>/<your theme>/template/catalog/navigation/top.phtml".
Add the below line before the line <?php echo $_menu ?>

<li class="home<?php if (Mage::helper('core/url')->getCurrentUrl() === Mage::helper('core/url')->getHomeUrl()):?> active<?php endif;?>"><a href="<?php echo $this->getUrl('')?>"><?php echo $this->__('Home') ?></a></li>