Meetup should use https (SSL/TLS) everywhere
Meetup should follow suit with Twitter and GMail (and other services), which now (by default) use https encryption (SSL/TLS) all the time when logged in. This would protect user accounts from being hijacked on an open WiFi network, and promote great privacy in general.
https everywhere, all the time is great if your connection and hardware support it. At the very least, make the connection secure every time the user logs in or you ask for a password (like when you ask me for my mobile # and password to sign up for SMS notification). You can even start off by offering it as an option like Google did with Gmail. Dang folks, respect your bloody users before you get sued. And yes you can use income from Organizers to make this happen.