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

window.onload = fix_external_links;