window.onload = target_blank;

function target_blank() {
	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;
			}
		}
	}
}