// This function looks for the 'external' rel attribute in an anchor and
// turns it into a new tab or window sort of link. (XHTML does not support
// this behavior natively for reasons of accessibility.)
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";
  }
}
addLoadEvent(externalLinks);