The La Trobe University hosts the Medieval Music Database, maintained by J Stinson. Searchable by feast, Saint, text, music and many others.
The Cantus database contains information about music for the Office. A simpler way to search Cantus is through this page.
If you are interested in medieval music from the low countries you should most certainly visit Chant behind the dikes maintained by Ike de Loos.
The Latin Vulgate bible can be search in many ways on this page
A paleography course is online available on Ductus
Willy Schuyesmans maintains this site containing various types of information on Gregorian chant.
When you are becoming an expert you surely want to visit the TML site.
An explanation on Gregorian chant notation can be found here.
Much information on medieval manuscripts can be found on the Medieval Manuscript Manual site
An very useful explanation on the Gregorian "modes" and many other topics can be found at the Gregorian Association web site
Many beautiful images of medieval manuscripts can be seen at the web.
Various manuscript images are available at the Bodleian Library, Oxford university, the Cary collection, and the Digital Scriptorum at Berkeley.
The Antiphonal site of the State Library of South Australia contains a lot of information on one single Antiphonal, including the images of all pages in various sizes.
There is even a Japanese site containing beautiful images.
Last update : 02-jan-2001