Inquisition - Introduction
An introduction to the origins of the Inquisition by David Burr.
http://www.fordham.edu/halsall/source/inquisition1.html

The Crime of Galileo: Indictment and Abjuration of 1633
Text of the Inquisition's charges against Galileo Galilei, provided by the Modern History Sourcebook.
http://www.fordham.edu/halsall/mod/1630galileo.html

Witchcraft Documents [15th Century]
Primary documents on witches and witchcraft from the Medieval Sourcebook.
http://www.fordham.edu/halsall/source/witches1.html

Catholic Encyclopedia: Inquisition
http://www.newadvent.org/cathen/08026a.htm

Tabula Rasa: The Inquisition
A short history from an esoteric perspective.
http://www.tabula-rasa.info/DarkAges/Inquisition.html

Nos Los Inquisidores - Harley L. McDevitt Collection on the Spanish Inquisition
Extensive collection of documents from the Spanish Inquisition, maintained at the University of Notre Dame in South Bend, Indiana.
http://www.rarebooks.nd.edu/exhibits/inquisition/

Historical Overview of the Inquisition
Article outlining the origins of the Inquisition and its Spanish and Roman variants.
http://galileo.rice.edu/chr/inquisition.html