Visual data: The digital revolution: first writing, images, & maps; now graphs

One of the neat developments of the digital era is the rapid advance of what geeks call the visual presentation of numerical information. Just as word processors revolutionized the mechanics of writing, Photoshop revolutionized image manipulation, and Google Earth revolutionized mapping, new digital tools are giving everyday users the power to produce amazingly useful and instructive interactive graphs. Two online newspapers produced beautiful examples this week: USA Today produced this interactive approval tracker comparing the approval rating for all US presidents since Harry Truman. The crimped screen shot reproduced here doesn't even hint at the power of this tool, so...