Hate to say it, but the video game industry isn't terribly welcoming for females in general. It's difficult to willingly insert yourself into an environment where you are the minority, and the majority makes it abundantly clear that it doesn't particularly care for your input (Not just gaming, and not just for women either). It's like putting a sign on your clubhouse that says "BOYS PREFERRED, BUT GIRLS PERMITTED IF THEY DON'T COMPLAIN". It's not an exclusive club, but it does more to deter them than entice them. If you want women to participate, you would have to actively encourage them to and help reverse the mindset that they shouldn't. It's not enough to leave the doors open for all and ignore all the previous bad blood that been incurred over the years. Again, that isn't just applicable for women and video games, either.
Also, some of the members' signatures and avatars don't... really help much. Seeing scantily clad women and bouncing boobs while trying to scroll through the boards isn't exactly appealing to most ladies, surprisingly enough! I've gotten used to it, having been following the industry for awhile, but ya gotta admit, most males would be none to keen on joining a board where the majority was women and several members per thread have a signature with homoerotic pictures of shirtless men.... hmm.... I might be giving myself ideas.