The following are good points of access for locating texts of ancient and early church writings:
CCEL - The mission of the Christian Classics Ethereal Library is to build up the church by making classic Christian writings available and promoting their use.
Guide to Early Church Documents - Guide to freely-available online resources relating to the early church, including canonical documents, creeds, the writings of the Apostolic Fathers and other historical texts relevant to church history.
Perseus - A project from Tufts University, the flagship collection of this digital library covers the history, literature and culture of the Greco-Roman world.
Sant'Agostino - A searchable database of the works of Augustine in Latin, Italian, English, Spanish, French, and Dutch.
