If you use the Drupal calendar module and wonder why the navigation links always link to the year 0000, there is a simple fix. Open up the file sites/all/modules/calender/theme/theme.inc and after this stanza (lines 19-23):

// Create the links to other displays.
$now = date_now();
$url = $view->get_url();
$view->date_info->url = $url;
$arg = $view->date_info->date_arg;

add the following line:

$view->date_info->year = $view->date_info->year && $view->date_info->year != $view->argument['date_argument']->options['wildcard'] ? $view->date_info->year : date_format($now, 'Y');