Chris Coyne (co-founder of keybase.io) seems to send them to new members. Unless he was on here, which is possible, I have no reason to suspect I received special treatment. It actually is fairly smart because you can grow your base by an order of magnitude and if you have set the culture of the people you invite, the site will blossom that way. I sent you an email to ask if you want an invite. If you get back to me I will send you one.