I read a statistic (I believe from Fender's research) half of new guitarists are female; that makes sense to me if you consider the amount of women who take up acoustic/are country music fans, but there seem to be more girls/women playing rock as well.
One band I recently got into in the doom/stoner metal genre has a female guitarist; Electric Wizard:
On the other side, Best Coast is a band I've listened to lately; sort of a surf-rock/60s retro thing: