// http://www.sitepoint.com/print/1041/

function externalLinks() {
  if (!document.getElementsByTagName) return;
  var anchors = document.getElementsByTagName('a');
  for (var i = 0; i < anchors.length; i++) {
    var anchor = anchors[i];
    if (anchor.getAttribute('href') && anchor.getAttribute('rel') == 'external') anchor.target = '_blank';
  }
}