As it turns out, I know about the same number of female atheists as I do male atheists. Actually, if I stopped to tally up the exact ratio I probably know more female atheists in person than I do their male counterparts.
Here's the thing though; if the numbers among nonbelievers is relatively equal, or at least it appears to me they may be, then why aren't there more books out there published by female atheists? Why aren't their more mainstream atheist female voices?
Almost all the books with regard to atheism, skepticism, and religious criticism are dominated by the male voice. As far as religious criticism goes, I know of Ayaan Hirsi Ali--and she has to have a fleet of body guards to protect her 24/7 for all the religious zealots out there waiting to lash out in hate and attack her (most of which are no doubt simple minded men). I know of Susan Jacoby and Valerie Tarico, but those are the only recognizable names that come to mind.
[Blag Hag provides a massive list of female atheists which you can be read here. I recognize less than half of the names on the list, but will continue to browse their writing with a keen interest.]
With but for the exception of some prominent scientific minded women like Marry Roach, Lisa Randall, Kayt Sukel, and other women of science, it seems there is a bias in the publishing industry favoring men toward women. I guess this isn't surprising, given the fact that men are still given the larger percentage of higher salaries and better job positions.
Maybe women are just softer spoken. Perhaps being "outspoken" or having the dire need to be vindicated in "being right" is a male trait. I suspect it may have something to do with the masculine domineering nature to argue--fight it out--and not back down from confrontation which makes men more suitable to publish something controversial.
On a similar note, it may also be the reason so many religious wars are waged--in the name of male superiority and the innate need to be right. It really does seem to be a man-made invention, all this religious business. Which may play a small part in why primarily men are so apt to criticize it. Although this is just an theory.
Another possible reason we see less female voices is perhaps because many women are involved with closely knitted social groups and networks where other women's opinions provide enough peer pressure to ensure they don't stick their necks out (too much) for fear of being ostracized.
Maybe it is because men (and not just religious patriarchs but men in all ages) have traditionally been extremely, and overly, cruel to women who do stick their necks out and voice their opinions.
I don't really know the answer here for why women nonbelievers do not share the same prolific followings as men or publish as frequently, but it certainly seems unfair.
Personally, I am growing rather more interested in the woman perspective and what women have to say. After all, it is she who has the most to gain from the emancipation of religion. In the near future I hope that women atheists, skeptics, and freethinkers start to get appreciated more, and maybe, get a few more book contracts as well.