From Sunlight Labs:
Despite the recent explosion of web based cartography tools, making effective maps for data visualization remains a challenge. While tools like Google Maps are great for helping navigate the world they are often poorly suited for thematic mapping, as many features like roads and cities only get in the way of telling compelling stories with data. In fact, even the distance between places can be a distraction – who cares how far away Alaska is when the goal is to make a simple comparison between US states?
Here’s the github project so you can play around: