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";	
 	}
}
window.onload = externalLinks; 

// <a href="http://www.abcde.com" onclick="window.open(this.href);return false;">abcde</a>