jQuery.fn.externalize = function(target, classname) {
    // Regular expression to match external url
    var isExternal = new RegExp("^http://" + location.host, "i");
    var isExternalAlternate = new RegExp("^http://www." + location.host, "i");
    $(this).each(function(){
        if (this.href.match("http://") && !isExternal.test(this.href) && !isExternalAlternate.test(this.href))
        {
            this.target = target;
            $(this).addClass(classname);
        }
    });
}