http://d.hatena.ne.jp/os0x/20090824/1251133041 にほんの少し手を加えた、UserScriptでwindowを取得するスニペット

gistfile1.js

(function(window, loaded){
    var win;
    if (!loaded && this.chrome) {
        var fn = '(' + arguments.callee.toString() + ')(this,true);';
        var script = document.createElement('script');
        script.appendChild(document.createTextNode(fn));
        document.body.appendChild(script);
        return;
    } else if (this.chrome) {
        win = window;
    } else {
        win = unsafeWindow;
    }
})(window);

gistfile2.coffee

((window, loaded) ->
    if not loaded and @chrome
        fn = '(' + arguments.callee.toString() + ')(this,true);'
        script = document.createElement('script')
        script.appendChild(document.createTextNode(fn))
        document.body.appendChild(script)
        return
    else if @chrome
        win = window
    else
        win = unsafeWindow
)(window)