Augustine left behind 5,000,000 words that survive today. To track individual titles, the scholar can use E. Dekkers, et al., Clavis Patrum Latinorum (Steenbrugge, Belgium, 1995 [3rd ed.]), or H.J. Frede, Kirchenschriftsteller (Freiburg, 1995 [4th ed.]). No complete English translation has ever been achieved of all his works. The Confessions, City of God, and selected letters are available in the Loeb Classical Library (Harvard University Press); a great many titles have appeared over the last fifty years in the series Fathers of the Church (The Catholic University of America Press); and a new series, The Works of St. Augustine: A Translation for the 21st Century, edited by John Rotelle, OSA, has begun appearing. For the scholarly reader, it is always worth looking at the lengthy (but also incomplete) French series, Bibliothèque Augustinienne, offering Latin text, French translation, and extensive annotation.
The largest web collection of Augustine's works in English the Select Library of Nicene and Post-Nicene Fathers: the translations are old and the set is far from comprehensive, but can be very useful. There are two CD-ROM collections that comprise Augustine's works in Latin (CETEDOC, published by Brepols, and Corpus Augustinianum Gissense [CAG], published by Schwabe} and the complete works in older editions may also be accessed on-line (at a very high price: typically available through subscriptions paid for by academic institutions for their members) in the Chadwyck-Healey "Patrologia Latina Database".) Latin texts of Confessions, de trinitate, and de civitate dei may be found on a site in Japan.
The Nuova Biblioteca Augustiniana has been publishing bilingual Latin/Italian editions of Augustine for many years and now has Latin texts and translations and much else of value available on an attractive site. To subscribe to their service offering updated information about the site, click on this link to send a mail message.
The Abbaye Saint Benoît de Port Valais in Switzerland maintains a site with French translations of the Confessions, City of God, On Baptism, The Trinity, and the Enarrations on the Psalms (May 2001: Psalms 1-50 included).
On this site, I maintain a limited selection of texts and translations as they have become available. News of possible additions always welcome.
City of God (de civitate Dei):
Christian Doctrine (de doctrina christiana):
Sermons (sermones: Latin texts only):
Sermons70-99 70 - (Mt. 11, 28-30)
De civitate Dei -- "City of God" (in Latin)
De vera religione -- "On True Religion" (in Latin)
Contra Faustum Manichaeum -- against Faustus, the Manichee (in Latin)
in Ioannis epistulam tractatus -- commentary on the first letter of John (in Latin)