The Orthodox Church Fathers offers a 38-volume collection of writings from the first 800 years of the Church, based on the "Early Church Fathers" section of the Christian Classics Ethereal Library CD-ROM. This collection is divided into three series, Ante-Nicene Fathers (ANF), Nicene and Post-Nicene Series I (NPNF1), and Nicene and Post-Nicene Series II (NPNF2).
The site as it exists now uses imperfect sources; the Ante-Nicene Fathers and Nicene and Post-Nicene Fathers were made by Protestants who ground a major axe against Rome, and so a passage where St. John Chrysostom scathingly denounces contraception is carefully mistranslated so it appears to refer soley to abortion. (See discussion.) Furthermore, to the Orthodox Church, the list of Church Fathers and their writing is not limited to early centuries: the list of Church Fathers continues almost as the great company of saints continues to grow. This collection was chosen due to copyright concerns, as the originally included works are in the public domain. (If you can obtain permission for other Church Fathers' works to be included, please contact me.) This is a valuable resource, but an imperfect one.
You can get all of the (original) HTML files on the CCEL CD-ROM. Also, Logos Research Systems publishes the Early Church Fathers in the Logos Library System for around $300 MSRP.