The Presbyterian Church, the Mennonites and the United Methodist Church, among several other organizations, provide directories of pastors online. They are usually divided by denomination, but a few independent organizations provide directories as well.
The Presbyterian Church provides a comprehensive list of pastors who have served the Presbytery, which can be navigated by searching for a pastor's first or last name.
The Mennonites use a directory that not only searches for ministers, but can also be used to find congregations, organizations or conferences by name.
The United Methodist Church has probably the most encompassing directory, which is able to search for a variety of subsections under the header sections of regional offices, denominational organizations, leadership, publications and ecumenical organizations.
Oneplace.com provides a directory of Internet centric ministries, as well as radio ministries. Listed alphabetically, this directory provides the names of ministers and information about the shows or podcasts they produce.