While there's always Monster, CareerBuilder and others for all kinds of jobs, I discovered several handfuls of sites devoted specifically to church ministry or Christian organization postings:
Church Staffing.com
Willow Creek Association Job Exchange
Simply Hired Ministry Positions
Staff Your Church
Pastor Search Network
Ministry Search.com
Ministry Jobs
Christian Jobs - MinistryEmployment.com
Kingdom Careers
Intercristo
MinistryList.com
Christian Career Center
Christianet.com
ChristianJobs.com
Christianity Today
Christian Employment Resource
Bethel Seminary
Manhattan Christian College
Christian Leadership Alliance