window.onload = externalLinks;
function externalLinks(){
if(!document.getElementsByTagName)return;
var links,a,i;
links=document.getElementsByTagName("a");
for(i=0;i<links.length;i++){
a=links[i];
if(a.getAttribute("rel")&&a.getAttribute("rel").indexOf("external") > -1){
a.onclick=function(){
window.open(this.href); 
return false;
}}}}