Extending Facet API for Mime Type 2

gistfile1.php

<?php
function MYMODULE_map_mime(array $values) {
  $map = $values;
  $mimes = array(
    'application/pdf'=>'PDF',
    'application/msword'=>'Word Document',
    'application/vnd.ms-excel'=>'Excel',
  );
  $map = array();

  foreach ($mimes  as $type => $name) {
    $map[$type] = $name;
  }
  return $map;
}