This is actually a suggestion that I Stumbled and have since lost, but is quick, easy and painless.
During your daily stumbling, get into the habit of clicking I like it!
for any atheist related item you see, even if you don't really read it or like it. What this will do is build the stats and increase the probability of it being presented to other stumblers. It is an easy way to spread atheism without really doing anything.
If you don't know what I'm talking about, go here