This site is geared toward deacons in the Community of Christ. It is NOT, however, an official site of any denomination, but represents the views of the author only. I hope to include information from deacons in other denominations as well. Hopefully, we can learn from each other.
In the Community of Christ, deacons are sort of free-lance ministers. While the duties of the other offices of the priesthood are clearly defined in the scriptures, a deacon's job description seems to be written in terms of what they can't do.
They are to "warn, expound, exhort, and teach, and invite all to come unto Christ", but they are not to "baptize, administer to sacrament, or lay on hands." [D&C Sec. 17]
Deacons may serve as the presiding officer of their branch, if elected. [Sec. 120] They are not to travel, however, but are expected to serve as standing ministers in their local groups along with the teachers. [D&C Sec. 83]
They may also serve as president of a deacon's quorum, a group of twelve deacons meeting together for study and fellowship. [D&C Sec. 104]
Deacons have been assigned other duties in the church, as well. In public worship, they are responsible for readying the building for worship, maintaining a comfortable atmosphere, and preventing disturbances. The deacons oversee the seating of the group and the collecting of offerings. When the service is over, they secure the building.
Administratively, deacons are the natural choice for treasurer. When the congregation owns its own building, deacons are to have contructive ownership. They may find it helpful to be aware of such things as building codes, zoning laws, and building maintenance.
Deacons serve as frontline financial ministers. They should be able to assist members with their financial planning and be aware of the various sources of financial assistance for those in need. As deacons counsel members regarding the stewardship of their talents and lives, they need some knowledge of career and vocational planning. As part of their home ministry, deacons are to be aware of the needs of members for assistance.
The duties of deacons in other denominations vary. In Roman Catholicism and Eastern Orthodoxy, their chief role is in assisting the priest in liturgical duties. Methodist deacons perform all pastoral duties except administering the Lord's Supper, while Presbyterian deacons manage their congregations' temporal affairs. Deacons in the Congregational and Baptist churches distribute communion, administer charities, and form the pastor's advisory council.