The Internet Encyclopedia of Philosophy
In addition to taking up contemporary Philosophy, this site also offers information on Medieval philosophy and philosophers (e.g. Avicenna, Augustine, etc.).
Philosophy Links on the Internet
This site provides access to resources related to Philosophy, categorized by topic, tradition, or time period. Particularly relevant is the link for Medieval Philosophy.
Philosophia Medii Aevi
This Italian site is dedicated to the study of Medieval culture and Philosophy. Included are links to related institutions (e.g. research centers); Italian scholars of Medieval Studies; conferences; publications; relevant resources; and calls for papers. Some entries are in English.
Stanford Encyclopedia of Philosophy
An extensive resource for philosophy and philosophical concepts, this site conveniently provides users with direct access to topics and notions related to the Middle Ages (in Table of Contents, search for the entry “Medieval Philosophy”).