drupal_summarize

function hdfs_summarise($paragraph, $limit) {
  $textfield = strtok($paragraph, " ");
  while ($textfield) {
    $text .= " $textfield";
    $words++;
    if (($words >= $limit) && ((substr($textfield, -1) == "!") || (substr($textfield, -1) == "."))) {
      break;
    }
    $textfield = strtok(" ");
  }
  return ltrim($text);
}

Added to the template.php in a drupal theme to truncate the body that it is put on in a theme like

<?php print THEMENAME_summarize($variablefield, 200); ?>