Magento - How to add a static link to the menu

Go to app/design/frontend/base/default/template/catalog/nav and open top.phtml

you will find this:

<div class="nav-container">

    <ul id="nav">

        <?php echo $_menu ?>

    </ul>

</div>

Go ahead and add your link before the </ul> making it:

<div class="nav-container">

    <ul id="nav">

        <?php echo $_menu ?>

<li class="level0 nav-5 level-top last"><a href='mylinkhere' target='_blank' class='level-top'><span>Link Title Here</span></a></li>

    </ul>

</div>