Modern Hagiography
Lives of the Saints by Alban Butler.
Lives of the Saints by Sabine Baring-Gould.
Our Birthday Bouquet Culled from the Shrines of the Saints and the Gardens of the Poets by Eleanor C. Donnelly.
Pictorial Half Hours with the Saints by Auguste François Lecanu.
Medieval Hagiography
The Cult of Saints in Late Antiquity Database
Letter from Sidonius Apollinaris about Bishop Mamertus instituting Rogation Days (scroll down to letter XIV)
Art & Architecture
Music
Cantus: A Database for Latin Ecclesiastical Chant
Customs & Traditions
Nihil sub sole novum 