I found McKinsey's report on Closing the tech gender gap interesting. It focuses a bit on the for-profit side, but I think there are some items in here that we can all do to lift up others, especially as we look at volunteer programs.
The evidence base points to eight components that programs need to incorporate to empower women and girls to succeed in tech. Tech companies should work with their partners to ensure these success factors are in place to maximize the impact of their investments: