Three Picks:	Williams, George H. The Radical Reformation (Sixteenth Century Journal Publishers, 1992; orig. pub. 1962)	Cohn, Norman The Pursuit of the Millennium (Oxford Univ. Press, 1989; orig. pub. 1957)	Friedrich, Otto The End of the World: A history (Fromm Int'l Publishing Corp., 1986)
More good ones:	George, Leonard Crimes of Perception: An encyclopedia of heresies & heretics (Paragon House, 1995)	Hill, Christopher The World Turned Upside Down: Radical ideas during the English Revolution (Viking Penguin, 1991)	x
.	Lambert, Malcolm Medieval Heresy: Popular movements from the Gregorian reform to the Reformation (Blackwell Publishers, 1992)	McGinn, Bernard Visions of the End: Apocalyptic Traditions in the Middle Ages (Columbia University Press, 1998; originally published 1979)	Lerner, Robert The Heresy of the Free Spirit in the Later Middle Ages (University of Notre Dame Press, 1991; originally published 1972)
.	Moore, R. I. The Birth of Popular Heresy (University of Toronto Press, 1995; originally published 1975)	Moore, R. I. The Origins of European Dissent (University of Toronto Press, 1994; originally published 1977)	Richards, Jeffrey Sex, Dissidence and Damnation: Minority groups in the Middle Ages (Routledge, 1995)