I'm not sure whether I read more female or more male writers, but I can say I've noticed more fantasy and science fiction novels published by female authors lately. Some of the ones I've read in the last few years include: Audrey Niffeneger (although her first book is probably in the literature category), Sarah Monette, Catherynne Valente, and Susanna Clarke. A long time ago, I used to read Sheri S. Tepper, and back then she seemed to be the one of the few female fantasy writers. Of course, there are plenty of female writers that do not limit themselves to these genres, although browsing back through my own personal reading list, I do not see as many.