This is for Sunnyvale residents but I am sure there are similar opportunities in other cities:
The City of Sunnyvale has a number of volunteer Board and Commission positions open. Here is what Boards and Commissions do (from website)
Boards and commissions recommend to City Council specific policy-related issues for possible Council study and action, and provide a forum and opportunity for broad community participation in the identification and prioritization of those issues. Boards and Commissions advise City Council on specific policy issues Council has chosen to study, and provide a forum and opportunity for broad community input on those issues.
The actual openings can be found here.
Since change starts local or at least can start local this might be a good way to get some experience working with local government. I am considering the Bicycle and Pedestrian Advisory Commission.
Santa Clara residents, here is a link for you.