How to make a 2-line menu link title?
You need to override theme_menu_link(), so in your template.php file from your theme put this code:

function MYTHEME_menu_link(array $variables) {
  $element = $variables['element'];
  $sub_menu = '';

  if ($element['#below']) {
    $sub_menu = drupal_render($element['#below']);
  }

  //Split titles using a &lt;br /&gt; when longer than 20 characters
  $element['#title'] = wordwrap($element['#title'], 20, "&lt;br /&gt;");
  //Set HTML to TRUE to display properly the HTML
  $element['#localized_options']['html'] = TRUE;

  $output = l($element['#title'], $element['#href'], $element['#localized_options']);
  return '&lt;li' . drupal_attributes($element['#attributes']) . '&gt;' . $output . $sub_menu . "&lt;/li&gt;\n";
}


Change MYTHEME by your theme name.
I used wordwrap() to split long menu title in small chunks but you can implement your own logic there.