A simple pills navigation:

<%= nav pills => [
            ['Item 1', ['#'] ],
            ['Item 2', ['#'], active ],
            ['Item 3', ['#'] ],
            ['Item 4', ['#'], disabled ],
        ]
%>
<ul class="nav nav-pills">
    <li><a href="#">Item 1</a></li>
    <li class="active"><a href="#">Item 2</a></li>
    <li><a href="#">Item 3</a></li>
    <li class="disabled"><a href="#">Item 4</a></li>
</ul>

A tab navigation with a menu:

<%= nav justified, id => 'my-nav', tabs => [
            ['Item 1', ['#'] ],
            ['Item 2', ['#'], active ],
            ['Item 3', ['#'] ],
            ['Dropdown', ['#'], caret, items => [
                    ['There are...', ['#'] ],
                    ['...three...', ['#'] ],
                    [],
                    ['...choices', ['#'] ],
                ],
            ],
        ]
%>
<ul class="nav nav-justified nav-tabs" id="my-nav">
    <li><a href="#">Item 1</a></li>
    <li class="active"><a href="#">Item 2</a></li>
    <li><a href="#">Item 3</a></li>
    <li class="dropdown">
        <a class="dropdown-toggle" data-toggle="dropdown" href="#">Dropdown <span class="caret"></span></a>
        <ul class="dropdown-menu">
            <li><a href="#">There are...</a></li>
            <li><a href="#">...three...</a></li>
            <li class="divider"></li>
            <li><a href="#">...choices</a></li>
        </ul>
    </li>
</ul>