What kind of jobs exist for Computer Scientists in social justice?
evgen: Stats.  Lots and lots of stats.  Get good at doing number crunching on big data sets using hadoop, R/incanter/etc and learning how to derive meaningful and defensible insights from all of the public data that is floating around out there.  Pick an org that suits your interests and see if they need help with general computer systems stuff while you work on a side-project that will impress them.  If you are good at it and this particular skill set interests you then you will also have a wide range of jobs to pick and choose from if you decide to go into the private sector.