Here are some community organizations:
Christian Coalition
Focus on the Family
Family Research Council
It could be argued that the Anbar Awakening (which has been just as important as the additional American men and women in uniform in Iraq) is a community organization.
When I lived in a small town in Colorado (I ran for school board, and lost, but in the process got almost 4x the number of votes that secured Governor Palin her mayorality), I was a member of a group of people who wanted to raise money to build a larger library. That was a community organization.
Now I belong to my neighborhood organization. I help people who don't know how to deal with the city bureaucracy contact the city arborist, advocate for brush removal to help kids who are walking to school get there more safely, arrange neighborhood garage sales, etc.