My wife doesn't participate in gaming forums like neogaf, but she does participate in other social forums.
She's not a particular fan of Facebook, and only uses it to play some of the games on there like Candy Crush or Farmville 2.
With that said, she is a pretty hardcore gamer. She plays Mass Effect, Fallout, Elder Scrolls, currently Diablo 3 on PS3, and she's still addicted to Terraria, which she's sunk a few hundred hours in on both PC and PS3.
She's mostly into RPGs, action or traditional, eastern or western. She's been gaming since she was a little girl, and she's 31 now. There are more female gamers than we give credit for, but many of them stay quiet and away from gaming forums because of various reasons, one of them being the general hostility, condescension, and sexism they receive. I'm sure there are plenty female members of gaf who have chosen to keep their sex to themselves because, well, it really does seem to change the conversation when people learn of the gender or race of posters. We may not think so, but it does happen, and I've seen it often in the past, here and otherwise.
I can understand why they'd want to remain anonymous. Female gamers are, to be quite honest, treated like they aren't "true" gamers, or that it's "cute" that they're dipping their toes into the gaming pool. And, oh, did you get into it because your boyfriend/husband/father/brother, etc, because, god forbid a woman be interested in anything that's not Barbies and pink. Only a man could introduce a woman to gaming!/sarcasm.
Me and my wife have this conversation often, as she is also huge into comic books and animation, and is a fan of many of the same things I am (ie, Batman, X-Men, Spider-Man, Archer, Samurai Champloo, Trigun, etc; she actually introduced me to Trigun because I'd never seen it).
NeoGAF is predominantly male because it is. Over time, there will probably be more females joining the ranks. It may never be an even spread, but it really shouldn't matter in the first place. I just hope that some of the condescension ("do you know what the "X" button does?" this was actually said to my wife by her supervisor when she worked at Activision and was testing games for them) and the often expressed sentiment that female gamers are only into "casual" games (I hear that one at the office all of the time by my fellow male co-workers, gets kept in check when they decide to reveal themselves and become a part of this community.