Depends...Drain STH was very good. L7 wasn't bad. Bangles. Jack Off Jill. If you're talking about all female's in a band.
Tina Weymouth from Talking Heads was an excellent bassist and I thought Chrissie Hynde from The Pretenders was as powerful a songwriter/vocalist fronting a band as most any guy.
I agree with nearly all of the points that have been made in this thread, except that it's really hard to tease out what part of someone's personality is genetics and what part is upbringing/societal expectations. When I majored in Psych. in college in the 80's (and listened to Talking Heads & The Pretenders (saw them in a great show at the Orpheum)), they told us that the big debate in the field was between people who believed in personalities being based in "nature" vs. those who thought they were based in "nurture". I think the thinking since then has leaned more toward nature, but that's partially because it's easier to just prescribe someone a pill and it's more profitable.
Everyone knows the emotional/nurturing vs. problem solving dynamic between men and women and a big part of that has to be biology. But, in terms of creativity and careers, as other people said, there's a lot of factors that influence people and society's expectations of women and men play a big part. I bet if you look at the biographies of Madame Curie and some of the women that broke the mold, you'd see things in their background that helped steer them that way, that it wasn't just genetics.
There's a lot more male nurses now than there used to be, and more female lawyers and doctors and Hollywood screenwriters.