inspect $wp_filter

<ul>
<?php

foreach ( $GLOBALS['wp_filter'] as $tag => $priority_sets )
{
  echo '<li><strong>' . $tag . '</strong><ul>' ;

  /* Each [priority] */
  foreach ( $priority_sets as $priority => $idxs ) {
    echo '<li>' . $priority . '<ul>';

    /* Each [callback] */
    foreach ( $idxs as $idx => $callback ) {
      if ( gettype($callback['function']) == 'object' ) $function = '{ closure }';
      else if ( is_array( $callback['function'] ) ) {
        $function = print_r( $callback['function'][0], true );
        $function .= ':: '.print_r( $callback['function'][1], true );
      }
      else $function = $callback['function'];
      echo '<li>' ;
      echo  $function ;
      echo '<i>' ;
      echo '(' ;
      echo  $callback['accepted_args'] ;
      echo ' arguments)</i></li>' ;
    }
    echo '</ul></li>';
  }
  echo '</ul></li>';
    }

?>
</ul>