"Refer a friend" button: okay. Bigger "refer a friend" button: I can take it. Forcing me to give my gmail password so that you can invite everybody I've ever emailed: NOT cool.
Over the last couple of years I've seen many sites use increasingly more aggressive tactics to get you to invite your friends to join the site. My favorite are the ones that innocently ask you for your gmail password (to save you time, of course), and don't quite tell you they're gonna email EVERYBODY you know saying "Luis is PERSONALLY inviting YOU to join!" I understand the desire to become viral, but at some point you have to wonder whether this actually works. From a psychological standpoint, I would assume it's not great to seem so...desperate?
So I'd like to try an experiment using the opposite tactic: making everybody want to join my highly exclusive, SECRET, site. If you join the site, the first rule is that you cannot tell ANYBODY about this site (like Fight Club). The only way to join is if somebody who is a member tells you the secret AND if all the current members vote you in once you know the secret. But that's the kicker: it's against the site rules for a member to tell anybody the secret, and if we find that a member told somebody the secret, we throw them out. So the only way for the site to grow is if the members secretively tell the secret and then lie about it. Let's see if we can make this grow faster than PushyWeb2.0SiteX.com.