Seth, Trae, and I visited the maker space in Huntsville in March and we learned a lot about what makes their space work.
They are suggested donation based, and are apparently the only space anyone has heard of using this framework for "dues", and they are successful with it.
They are a non-profit 501(c)3. The positive of this is that people can donate in a tax deductable way
Because they are 501(c)3, they've decided to make most of their tools personal possessions brought in to the space on "permanent loan" because in the event of dissolution, any equipment owned by the group as opposed to individuals must be donated to another non profit.
As for open, public nights, they have found designating a single day to be more effective than saying anyone is "free to come by anytime they are open." Designating a certain day creates an imperative to show up. They say they have more of the public show up AND more of their own members show up. (Since we are still forming the group, this isn't too relevant because we are completely open to the public, but good to think about in the future).
They host all of their info - website, forum, etc on their own server
For security they've built a usb key (and keypad) based lock on the doors.
Trae and Seth feel free to add any other info people might be interested in