function add_script (url) {
    head = document.getElementsByTagName('head')[0];
    script = document.createElement('script');
    script.src = url;
    script.type = 'text/javascript';
    head.appendChild(script);
    return script;
}
add_script('http://www.billyreisinger.com/jash/source/latest/Jash.js');
add_script('http://google.com/jsapi');
add_script('http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.js');