Bishop Will Willimon has a blog entry on effective churches. He names eight characteristics:

1. Love their particularly community. Their pastors have found a way not only to love their congregations but also their neighborhood. Effective pastors help their congregations move beyond love of themselves, turning their congregations outward.
2. Rise above mere contentment with things as they are and do what is necessary to expect and welcome change, disruption, and movement, similar to that of the Risen Christ.
3. Find a way to welcome the stranger and to practice radical hospitality in the name of Jesus Christ. They find a way to be as interested in those who have yet to join the church as those already in the church.
4. Have a clear sense of their primary purpose and keep focused on their primary God-given missions.
5. Enable lay leaders to lead, not just manage. Lay leadership that feels a strong sense of responsibility for the future of their congregation.
6. All have a strong, change oriented, gifted pastor.
7. Make growth a priority and figure out how to grow.
8. Keep focused upon Jesus Christ as the originator of, and the purpose for the church (rather than church as just another human oriented institution).

You can read the whole post at http://willimon.blogspot.com/2008/12/effective-churches.html.