The publications department at the Pontifical Institute of Mediaeval Studies in Toronto (PIMS) has placed some PDF versions of the annual Etienne Gilson Lecture onto their site for free downloading. Every year the Institute invites a senior medievalist to deliver the lecture—this spring's lecture was by M. Michèle Mulchahey—and thereafter publishes the lecture in a small booklet. Leonard Boyle's epic The Setting of the Summa theologiae of Saint Thomas (link), published many times, first saw light as this lecture, as did Mark Jordan's The Alleged Aristotelianism of Thomas Aquinas (link). The Institute provides a separate page devoted to it, which includes the detailed on the following past lectures, and links to the PDF versions of their lectures. Here is a sampling:

• 2000: Marcia L. Colish. Remapping Scholasticism. Etienne Gilson Series 21. 2000; 21 pages. ISBN 0–88844–721–3. Available in a PDF version.
• 2002: Francis Oakley. Omnipotence and Promise: The Legacy of the Scholastic Distinction of Powers. Etienne Gilson Series 23. 2002; 28 pages. ISBN 0–88844–723–X. Available in a PDF version.
• 2004: Karl F. Morrison. The Male Gaze and Other Reasons for the Hypothetical End of Christian Art in the West. Etienne Gilson Series 26. 2005. 36 pages. ISBN 0–88844–726–4. Available in a PDF version.
• Related Lecture (NOTE: not a Gilson Lecture, but a fine one, indeed): Anthony J. Celano. From Priam to the Good Thief. The Significance of a Single Event in Greek Ethics and Medieval Moral Teaching. EGS 22 / Studies in Medieval Moral Teaching 2. 2001. 24pp. ISBN 0–88844–722–1. Available in a PDF version.

Of related interest is this: PIMS has republished nine of these lectures in a single volume as part of its Spring 2008 catalog of publications. This volume includes the lectures of the well-known Thomists, Leonard Boyle, Edward Synan, James Weisheipl, Mark Jordan, and James P. Reilly.