I'm using the Themed Login Plugin and it works great except for one thing. The plugin does not check to see if the 'anyone can register' option is enabled. I have that option disabled and do not want the registration form to show so I added the following code to the jk_do_register function just after the globals:
if ( FALSE == get_option('users_can_register') ) {
$header_files = get_option("jk_login_header_files");
foreach((array)$header_files as $header_file)
include(TEMPLATEPATH . '/' . $header_file);
echo get_option("jk_login_after_head_html");
echo('<h2>Registration is closed</h2>');
echo get_option("jk_login_before_foot_html");
$footer_files = get_option("jk_login_footer_files");
foreach((array)$footer_files as $footer_file)
include(TEMPLATEPATH . '/' . $footer_file);
exit();
}