Another thought: allow members to sign up to act as greeter for the
weekly party. Each week, we try to always have one greeter signed up,
and their job is simply to definitely attend the weekly party and say
hi to people when they show up. Just a simple "Hello! Are you here for
the Sudo Room party?" would be sufficient. You'd just need to promise
to be present and greeting whoever arrives from say 7pm to 9pm.