Oxford Companion to the History of Modern Science [online]

Companion encyclopedia of the history of medicine / edited by W.F. Bynum and Roy Porter. 1993. [a good starting place for addressing any topic in the history of the health sciences]
 
The greatest benefit to mankind : a medical history of humanity / Roy Porter. 1997. Arguably, the best single volume text on the history of medicine.

The Evolution of Modern Medicine / Sir William Osler. 1913 [online].  A highly readable history of medicine through the first decade of the 20th century

A dictionary of the history of medicine / Anton Sebastian. 1999.  

Encyclopedia of medical history / Roderick E. McGrew, with the collaboration of Margaret P. McGrew. 1985. 

Nursing, the finest art:  an illustrated history / M. Patricia Donahue. 1996.

Historical encyclopedia of nursing / Mary Jane Snodgrass. 1999.

The medical almanac : a calendar of dates of significance to the profession of medicine, including fascinating illustrations, medical milestones, dates of birth and death of notable physicians, brief biographical sketches, quotations, and assorted medical curiosities and trivia / Pasquale Accardo. 1992.

HyperHistory Online. Allows users to construct their own timelines based on subject preferences

A chronology of medicine and related sciences / Leslie T. Morton and Robert J. Moore. 1997. 

Dates in medicine; a chronological record of medical progress over three millennia / edited by Anton Sebastian. 2000.

Oxford dictionary of medical quotations / Peter McDonald. 2004. 

Familiar medical quotations / edited by Maurice B. Strauss. 1968.

Medicine in quotations : views of health and disease through the ages / edited by Edward J. Huth, T. Jock Murray. 2000. 

Medically speaking : a dictionary of quotations on dentistry, medicine, and nursing / selected and arranged by Carl C Gaither and Alma E Cavazos-Gaither ; illustrated by Andrew Slocombe. 1999.

Dictionary of medical biography / edited by W. F. Bynum and Helen Bynum. 2007.

The Nobel Prize winners. Physiology or medicine / edited by Frank N. Magill. 1991.

A biographical history of medicine: excerpts and essays on the men and their work / [by] John H. Talbott. 1970.

Oxford Dictionary of National Biography [online]
"56,000 biographies of people who shaped the history of the British Isles and beyond, from the earliest times to the year 2004."

American Nurses Association - Hall of Fame.  Thumbnail sketches of the most prominent American nurses from the 19th century to the present.

Dictionary of American nursing biography / Martin Kaufman. 1988.