$app/bin           your main script and/or associated utilities
$app/etc           configuration files, persistent state
$app/lib           all of your modules or 3rd-party modules
                   you need to bundle
$app/var           any misc. state or files you create/use
                   at run-time (if any)
$app/doc           documentation (though a README or INSTALL
                   would be nice in $app/)
$app/htdocs        the web 'root' of your application, attached
                   to your web site using server configuration