You're in luck! In most cities, there are Code for America "Brigades" that are meetup groups where people can work on digital public service projects.
http://www.codeforamerica.org/brigade/
For example, I'm in the SF brigade and work on the BallotAPI project.
Re:Join the U.S. Digital Service
by catherinedevlin on Tuesday February 03, 2015 @12:52AM
(#8989072)
Well, there is Code for America. That's a volunteer organization not actually within the government, so it's not a terribly close analogy, but it's still one means of digital civic service that stops short of full-time.
Hell, if they did that, I'd probably serve after my time in the Guard is up.