The problem with this is there's no accountability. It's not like a book club where you can hassle the other people for not reading the book, or a film club where you're all watching the film together.
However, I will say that the idea of selecting a film for a given month is a better idea than has been proposed in the past, as it eliminates the second big issue, which was time. Usually we'd give people a much more limited deadline to watch the film, and people wouldn't be able to. Having a film -- or even a couple of films that are thematically or creatively linked -- a month is a much better approach to that. People can watch, and discuss on their own time during that month.
I also want to say "let's not get too ambitious right off." We should be working our way up to the Qatsi Trilogy and El Topo, not starting off with those. Our first couple of films should be accessible and allow for as many people as possible to participate in the discussion. On the other hand, you don't want to make it too broad -- I remember we started off with Citizen Kane last time and there was some great discussion, but even then, it felt like we were doing Film Studies 101, which I don't think a lot of people come here for.
Having people sign up and know in advance is a good way to go; good way to allow the discussion to begin stewing in the brain. I also like Phil's suggestion of going to the CHUD lists (also, Beaks Canon).
Of the films that have been mentioned, Nashville and Right Stuff, which are both long but accessible and there's a lot of different things that can be said about both of those. Also, they're masterpieces. I'd also throw in Red River as an idea.
As I said in the main thread, I'm up for this but there are some bugs that should be worked out first.