I find myself becoming more "activist" in my atheism too, but all that really amounts to is being more "out" about it. What I would really like to accomplish is to make discrimination against atheists as socially unacceptable as discrimination against other minority groups is. An atheist should be able to openly run for public office without the mere fact of their atheism ensuring they will lose. Business people wouldn't dream (in today's world) of posting anti-semitic jokes on a business forum, but they think nothing of posting anti-atheist jokes there.
We will never entirely rid the world of bigots, but I would like to work towards a world were bigots are the only ones that are marginalized.