Changing text "Create new account" in /user tab
By writing a custom module that implements hook_menu_alter and alter the title of the menu.
Something like below.

mymodule_menu_alter(&amp;$items) {
  $items['user/register']['title'] = 'New Text';
}


http://api.drupal.org/api/drupal/modules--system--system.api.php/function/hook_menu_alter/7