A few people have asked me this question just this past week. I usually point them to this thread in the forums. Any other suggestions?
Q. What schooling should I take to learn about visualization and data graphics?
Think Like a Statistician – Without the Math
I call myself a statistician, because, well, I’m a statistics graduate student. However, the most important things I’ve learned are less formal, but have proven extremely useful when working/playing with data.