I just went to a Bar-Mitzvah for my 3rd cousin (or something like that) and it was a whole weekend ordeal. When I was watching the Orthodox temple service, they all were singing harmoniously and stomping their feet to the rhythm while having their arms around their fellow temple members; it made me really miss that whole feeling. It really was the first time that I missed being Jewish just because I know that Atheists or Agnostics don't organize to praise anything, if so its not in a serious way. This all was a unified feeling and it was all so happy! I think that part of what made it so nice was that whenever they referenced God they said Hashem so I never got that "someones talking about God..." alert to my brain( like the one you get when someone says your name and you are immediately called to attention).
I don't really know if their could or should be an alternative organization for non-religious people because it wouldn't really be of the same feeling but I was just wondering if anyone just misses the sense of community that organized religion can bring.