function externallinks() {
   var atags = document.getElementsByTagName('a');
   for(var i=0;i<atags.length;i++) {
      if(atags[i].rel.indexOf('external')>=0) {
	atags[i].onclick=function() {window.open(this.href); return false; }
	atags[i].title=atags[i].innerHTML+' - will open in new window/tab';
	atags[i].className = 'newwindow';
      }
   }
}

window.onload=externallinks;