I support this wholeheartedly:
An annoying but intrinsic property of atheists is that we are all horribly fractured — this is a disparate group with no central leadership, and that's the way we like it — but it also means our presence is fragmented and easier to ignore. We have all these different godless organizations with different national meetings that overlap and often share members, but no coherence. Margaret Downey has been pushing an idea for a little while that you can read about in a post on the Friendly Atheist from last year: we should all at least once get together in one giant massive united meeting and make a show of our numbers and our common goals.
It's been a struggle to get this together. The initial plan was to do it in 2010, but that's not going to happen; the proposal now is to stage a Unity Convention in 2013 in Washington, DC. All the national non-theist organizations would coordinate for this event and bring their memberships together in one gathering, one grand mega-meeting in which we'd let the leaders of the country know that we're here and we're watching them and we vote.
I think it's a fabulous idea. I'd go. How many of you would join us? We could all join hands in the Mall and make a joyful noise for humanity and reason, and then adjourn to the Smithsonian for some tasty science. If you like the idea, leave an endorsement here or at Hemant's site…and, I might add, if you're a member of one of the many atheist groups in the US, let your leadership know you want to be able to share the dream with everyone else.