It looks like they already have a gittir chat room: https://gitter.im/mholt/caddy https://gitter.im/mholt/caddy. I'm not sure if Gittir supports gating access

It looks like they already have a gittir chat room: https://gitter.im/mholt/caddy https://gitter.im/mholt/caddy. I'm not sure if Gittir supports gating access like you mention, but I think some of the other suggestions here might even be more promising. The advice by patio11 comes to mind: "You should sell something." This something should be a substantial product offering; something more than access to an "exclusive club hangout room."