Christian Classics Ethereal Library:
Extremely helpful source of primary texts in church history, Christian spirituality, Christian music, and more
Christian History: http://www.christianhistorymagazine.org.
Lectio Divina: Christian Spiritual Authors:
Index page of sources for spiritual reading; many good primary texts in early Christian theology and spirituality.
The Holy See:
Official Website of the Holy See: papal and curial documents in different languages.
"A Hypertext Encyclopedia of Early Church History" (and primary texts)
Christian Art, The Holy Land, Papal Documents
Patristic Texts, The 1908 Catholic Encyclopedia, Hagiography
The Spiritual Exercises, St. Ignatius, Ignatian spirituality, and more.
The Golden Legend, published 1483
(articles and complete text of Spiritual Theology and Christian
Spirituality in the Catholic Tradition
Archive: (Many, many out-of-print texts and other media)