I hack on Free (as in freedom) Software because I know it makes the world a better place. Proprietary software is only meant to exert force over those that use it, while free + open source software gives people the freedom to learn and modify.
If you are interested in a more detailed description of some of my achievements, I have an outline here.
I also mentor students via Google Summer of Code and Google Code In, which are programs that introduce college and high school students to the world of Free and Open Source software. I do this because I know it makes the world a better place.
I am always interested in giving talks and presentations about the various subjects. If you would like me to talk about something at your user group, meetup, (un)conference, or whatever, please feel free to contact me.