The Josephinum has one of the largest collections of medical moulages (anatomical wax models) in the world outside of Florence, and it is exquisite; probably not for the faint of heart, however.  The collection was originally put together in the 18th century as a teaching tool for medical students in Vienna and graphically depicts dissections on cadaver-like models.  It is a little difficult to find, but if you are persistent, you will reach the right building and go up the two or three flights of stairs and pay your 2 euros to the attendant.  It takes about a half an hour to view the collection.  Recommended over the Sigmund Freud House Museum several blocks away, which is expensive and contains very little of Freud's own furniture.