The Catholic Encyclopedia is a wonderfully rich source of information. Obviously its articles are written from a Catholic perspective and need to be read with that in mind, but generally are thorough and scholarly. This is especially true with respect to those which treat historical matters. http://www.newadvent.org/cathen/ .  Try the tabs in the upper right corner of the home page. “Encyclopedia” has good articles on a multitude of subjects from church history. “Fathers” has an alphabetical index which leads to dozens of sources from the ancient period of the church (up to about AD 600).

Christian Classics Ethereal Library includes many ancient Christian sources. The “browse by author” feature is very helpful in locating specific works.  http://www.ccel.org/ 

http://www.iclnet.org/pub/resources/christian-history.html  Site directs you to many original sources for apostolic fathers and apologists.

Tertullian  This site is a valuable source of information on Tertullian and his extant works (33 of them). This site also redirects you to English translations of his works also available on the internet. http://www.tertullian.org/

Irenaeus’ Against Heretics  http://www.gnosis.org/library/advh1.htm or http://www.newadvent.org/cathen/ .

http://www.ntcanon.org/index.shtml  This site is an excellent source of information about and English translations of non-canonical Christian works (the Apostolic Fathers) as well as various New Testament Apocryphal works, such as the Gospel of Thomas, Gospel of the Egyptians, Acts of Paul, Acts of Andrew.

The Gospel of Judas http://www.nationalgeographic.com/lostgospel/index.html

The Gospel of Mary Magdalene http://www.gnosis.org/library/marygosp.htm

Roman and Greek Classic Authors: http://classics.mit.edu/Browse/index.html a excellent source for English translations of the major works of Greek and Latin classical authors. Those included here who are of particular interest in the study of early Christianity are: Plutarch, Strabo, Diodorus, Tacitus, Livy, Josephus.  Suetonius’  Lives of the Twelve Caesars, is not included on this site but may be found at http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Suetonius/12Caesars/home.html. The work of Dio Cassius is at http://onlinebooks.library.upenn.edu/webbin/gutbook/lookup?num=10890