Here's a recent New York Times article entitled "A Toolkit for Women Seeking a Raise:"
It's an interesting article because it gives practical solutions to the problem that women and men are treated differently when they negotiate. After all, as the article says, "research shows that [women] are less likely to ask for raises. Even when they do, their requests may be perceived as overly demanding or less agreeable."
Also, "You may be asking yourself, as I did, whether negotiating in ways more favorable for women means that we’re just succumbing to stereotypes — or whether the ends justify the means." I don't think that the article really answers this question that well, but it does present good practical ways to get what you need. Go read the article.