Internet Medieval Sourcebook (Fordham University). 
The WWW Virtual Library History Index:  Medieval History
ORB:  The Medieval Encyclopedia
Labyrinth:  Resources for Medieval Studies
Netserf:  Hypertext Medieval Terms Glossary
The Catholic Encyclopedia -- search on any topic or term. 
This Day in Medieval History -- a list of all important events in medieval history on the current date.
Medieval Web Rings.
Three Views on Feudalism (lecture/reading).
The Peoples of the "Dark Ages."
Castles on the Web.
Odin's Castle of Dreams and Legends.
Ian's Land of Castles.
Chivalry, Knighthood, and Castles (reading),
An Intro. to the Fief and Castle.
Medieval Fiefdom (ThinkQuest project).
A Feudal WebQuest:  Medieval Europe & Japan.
Feudal Institutions.
The Feudal Structure of the Medieval World.
The Rise of the Western Church (lecture/reading).
The Life of St. Gregory the Great (reading).
St. John the Divine Cathedral, NYC -- a pilgrimage back to the Middle Ages just around the corner.
The Gregorian Chant Home Page.
St. Benedict and His Order.
The "Confessio" of St. Patrick.
Hill Monastic Manuscript Library (St. John's Univ., MD).
The Monastery of Christ in the Desert.
MATRIX:  Resources for the Study of Women's Religious Communities.
Hildegard of Bingen.
The Pilgrimage to Santiago de Compostela -- become a pilgrim and journey along the same road to Compostela in Spain that medieval pilgrims took (some parts are in Spanish).
The Bayeux Tapestry.
The Lindisfarne Gospels.
Earthlore Explorations:  Gothic Architecture.
Medieval Culture as Evidenced by Gargoyles.
Medieval Art -- a lot of good links to Medieval art, architecture, crafts, tapestries, etc. 
The Knighthood, Chivalry, & Tournament Resource Library.
Wharram Percy:  The Lost Medieval Village.
Medieval Domestic Life
Medieval Jobs.
Health in the Middle Ages.
Medieval English Towns.
The Medieval Marketplace.
Footwear of the Middle Ages
Medieval Card and Board Games.
A Boke of Gode Cookery (A Book of Good Cookery) -- a great page of medieval cooking, recipes, etc.
Medieval/Renaissance Food Page -- includes medieval recipes.
Dominion & Domination of the Gentle Sex:  The Lives of Medieval Women.
The Birth of the University (lecture/reading).
The Medieval Technology Page.
Women Writers of the Middle Ages.
Women Artists of the Middle Ages (essay).
A Medieval Love Story.
Courtly Love.
Medieval Irish Poetry.
Bulfinch's Mythology:  The Age of Chivalry or the Legends of King Arthur.
Bulfinch's Mythology:  Legends of Charlemagne or Romance of the Middle Ages.
Medieval Drama Links.
Tales of the Middle Ages.
A Concise Guide to Medieval Instruments.
Medieval & Renaissance Europe Primary Source Documents.
Anglo-Saxon Culture.
Anglo-Saxon England.
Celts & Saxons Homepage.
Charlemagne -- a lot of good links about his life and times.
Charlemagne's Biography.
Charlemagne (Catholic Encyclopedia).
The Vikings Network (index page).
Vikings and Stuff.
The Viking Longship.
The Battle of Hastings, 1066.
The Crusades:  Five Centuries of Holy Wars.
The First Crusade (lecture/reading).
The Knights Templar.
Some Achievements of Medieval Europe (lecture/reading/a professor's personal view).
Medieval Clip Art.