function externalLinks() {
	if (!document.getElementsByTagName) return;
	
	var anker = document.getElementsByTagName("a");
	
	for (var i=0; i<anker.length; i++) {
		var anchor = anker[i];
		
		if (anchor.getAttribute("href") && anchor.getAttribute("rel") == "external")
			anchor.target = "_blank";
	}
}

window.onload = externalLinks;