I download the Almost Users Only plugin and configured the info URL, but upon going to the site you get the error:
Warning: Cannot modify header information - headers already sent by (output started at /home/imagina/public_html/app/wp-content/themes/twentyeleven/header.php:13) in /home/imagina/public_html/app/wp-includes/pluggable.php on line 876
I am also using the "Hum" theme. (http://wordpress.org/themes/hum)