Create blocks of first items of main-menu

bluecollar_helper.module

<?php
/**
 * Implements hook_block_info().
 */
function bluecollar_helper_block_info() {
/*  $blocks['bluecollar_resource_filter'] = array(
    'info'  => t('Resource Filter'),
    'cache' => DRUPAL_CACHE_PER_ROLE,
  );
*/
  $main_menu = menu_tree('main-menu');
  foreach (element_children($main_menu) as $key => $item) {
    $blocks['bluecollar_submenu_' . $key] = array(
      'info'  => t('Bluecollar Submenu ' .$key),
      'cache' => DRUPAL_CACHE_PER_ROLE,
    );
  }

  return $blocks;
}

/**
 * Implements hook_block_view().
 */
function bluecollar_helper_block_view($delta = '') {
  $block = array();

/*  switch ($delta) {
    case 'bluecollar_resource_filter':
      $block['subject'] = t('Resources');
      $block['content'] = bluecollar_helper_resource_filter();
      break;
  }*/

  $main_menu = menu_tree('main-menu');
  foreach (element_children($main_menu) as $key => $item) {
    if ($delta == 'bluecollar_submenu_' . $key) {
      $block['subject'] = $main_menu[$item]['#title'];
      $block['content'] = bluecollar_helper_submenu($key);
    }
  }

  return $block;
}

function bluecollar_helper_submenu($key) {
  $main_menu = menu_tree('main-menu');
  $menu_keys = array_keys($main_menu);
  if (isset($main_menu[$menu_keys[$key]]['#below'])) {
    return drupal_render($main_menu[$menu_keys[$key]]['#below']);
  }

  return FALSE;
}