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" ) )
    {
      var value = anchor.getAttribute( "rel" );
      if ( value == "nofollow external" ) 
      {
        // For Firefox
        anchor.target = "_blank";
      }
      else if ( value.search( "external" ) > 0 )
      {
        // For IE 
        anchor.target = "_blank";
      }
    }
  }
}
window.onload = externalLinks;