Even if they can't be herded, cats in sufficient numbers can make a lot of noise and they cannot be ignored.
Cincinnati Zoo's change of heart about hopping into bed with the Creation Museum after a number of complaints, many from readers of PZ Myer's Pharyngula, is proof that Dawkins is really onto something, and is an excellent example of what can be achieved with a little organization. Many others have realized this, and atheist communities are starting to spring up and grow (several of them are linked on the right). I'm a member of two at the moment, The Brights (a "constituency of individuals who share a naturalistic worldview"), and Atheist Nexus (an atheist myspace/facebook). Joining these communities is a quick and simple way to make a lot of noise. They are a good way of meeting like-minded people, keeping up to date on relevant issues, raising money for worthwhile causes and just generally helping to give atheists more of a presence in the world. Have a think about joining one today.