That theme uses pages for the dynamic menu, right?
You can do this: http://wordpress.org/extend/plugins/page-links-to/
Which is probably the easiest 🙂
Off the cuff …
You will have to edit the function sandbox_globalnav() in the functions.php template file.
function sandbox_globalnav() {
if ( $menu = str_replace( array( "\r", "\n", "\t" ), '', wp_list_pages('title_li=&sort_column=menu_order&echo=0') ) )
$menu = '<ul>' . $menu . '</ul>';
$menu = '<div id="menu">' . $menu . "</div>\n";
echo apply_filters( 'globalnav_menu', $menu ); // Filter to override default globalnav: globalnav_menu
}
Change the line: $menu = '<ul>' . $menu . '</ul>'; to:
$menu = '<ul>' . $menu . '<li><a href="http://link-to-your-gallery">Gallery Link</a></li>' . '</ul>';
… untested, but it should work (or at least get you started) …
Thank you both of you! Very helpful!