Since human beings relate to the world spatially, maps are a powerful tool for analysis and sense making.They can also be beautiful works of art in their own right.
Here’s a wonderful resource: Places and Spaces: Mapping Science, a 10-year effort to build a collection of maps to encourage a “cross-disciplinary discussion on how to best track and communicate human activity and scientific progress on a global scale.” The maps are physical artifacts but the online gallery is deep and very well done.
The variety of representation modes in the collection is very broad, ranging from things we would recognize as maps, to Mignard’s “Napoleon’s March to Moscow” chart made famous by Tufte, to some visualizations whose beauty may outstrip their explanatory power such as this one by Ingo Günther.
For a good book on the subject of maps and science, check out Atlas of Science: Visualizing What We Know