The Mutter Museum offers a variety of medical history online. Sponsored by the College of Physicians of Philadephia, it includes photos and timelines. Also available is a brochure about their medicinal garden, which includes a number of plants that have proven helpful over time.
A special exhibit focuses on the History of Vaccines. This site includes a number of photos relating to polio and a timeline of important events in disease control.
In addition their blog features a neat National History Day 2012 second place video winner called "Salk Vaccine Trials." The students covered the emergence of the polio epidemic, causing 20,000 cases per year, through the creation of the Salk vaccine.