Some other great organizations helping set examples and mentor high schoolers:
She++: http://sheplusplus.stanford.edu/
MentorNet: http://www.mentornet.net/
MentorSET: http://www.mentorset.org.uk/
Technovation: http://iridescentlearning.org/programs/technovation-challeng...
MIT: http://swe.mit.edu/outreach/
There are also several great organizations for women working in computing, who you could reach out to for mentors. PyLadies, DevChix, Systers, Anita Borg, etc... And local tech companies, at Google there were several folks working with local high schools who would put out internal calls for people to go and speak about the cool stuff they worked on.
Speaking of which, Google's Women Techmakers is also shaping up to be a great collection of women doing cool stuff in tech: https://developers.google.com/women-techmakers and https://plus.google.com/communities/100202454944694552166
I am volunteering with a local "Code Club" to teach programming to 8-14 year olds. We have just tried to be open and gender neutral, ending up with between 10-25% female depending on the week. Purely subjective opinion, but Jessica Yuen from the Khan Academy (https://www.khanacademy.org/talks-and-interviews/other-featu...) tutorials has been a huge example for these children (boys and girls).
I'd love to profile more examples in our code club sessions. Does anyone know of a central source for people willing to volunteer as "examples" for young computer scientists? If not, maybe we can start a google doc or something?