Other
Boolean Propositional Logic
Introduction to classic, boolean propositional logic. Written in a clear way with little or no technical notation. A great place to start for those beginning to learn about logic.
Wikimedia
Wikipedia: George Boole
This site from Wikipedia provides an in-depth look at the life, accomplishments, and ideas of mathematician George Boole. It discusses his publications on mathematics and logics, has information on his analogy between the symbols of...
University of St. Andrews (UK)
University of St. Andrews: John Venn
Good introduction to Venn's life and work. Explains especially his lifelong relationship to Cambridge. Includes links to further information on Venn's "probability theory."