Suzette Haden Elgin
Linguist and writer Suzette Haden Elgin is probably best known for her books on the "Gentle Art of Verbal Self-Defense", but she has also written several compelling social science fiction books.
Native Tongue
Native Tongue is Elgin's first book in the Native Tongue trilogy, set in the future (or an alternate universe) when women and men lead separate lives and women are considered inferior. The women develop their own language and eventually (of course) save the world.
Judas Rose
Judas Rose is the second in the Native Tongue trilogy, and it continues the theme of women attempting to overcome the destructive nature of men's society (sorry, guys, just remember--it's only a novel).
Earthsong
Haden Elgin's third book in the Native Tongue trilogy takes the power of language out beyond the ability to protect and maintain a culture under extreme suppression to an amazing degree. And if I say anything more, I'll spoil it.