I've enjoyed reading Edward Tufte's books about displaying information effectively and have found them immensely informative and helpful for my work. I encourage anyone, no matter what your professional background, to purchase and study any of his books (you should probably start with Envisioning Information).
Earlier today I was pointed to Style.org by Steven via a Slashdot article. Jonathan Corum, who wrote all three articles on the site, certainly understands the principles Edward Tufte expresses. Corum's illustrations of winged motion and electoral districts are refreshingly simple and effective. Note in the illustration below (see the original image) how the solid line intuitively indicates the power in the down stroke and the dotted line indicates the passive recovery. The time-distance sequence is also subtle yet informative. All together very nice.