One of the speakers at our upcoming Digital Humanities + Data Journalism Symposium is Ben Schmidt, a professor at Northeastern University. Ben is a historian, and he uses data and visualization broadly and smartly. A while back he got a lot of media attention for this project about gendered language in RateMyProfessor.com reviews.
My favorite among his visualizations is the map of shipping paths shown below. It's pure graphic poetry. You shouldn't miss the other projects showcased in his personal gallery.