I am fascinated with the depiction and transfer of information, one of my life-long interests. I am one of the few people I've ever met who enjoyed Microeconomics more than Macroeconomics, mostly for the graphic models. I went back to grad school after I had already received my Master's and took a class entitled "Quantitative Decision Modeling" because I thought it sounded FUN. It was. One of my favorite jobs included creating statistical process charts of internal processes for quality improvement purposes. Never met a chart or a method of producing one that I didn't salivate over.
So when I say that this is the best graph ever, I'm right. :o) Naturally, the fellow (Edward Tufte) who sells this poster thinks so, too (oh alright, I first discovered this graph reading his awesome book).
To really appreciate it, you must check out his book or order the poster. Tufte did not create this graph--it was created by a Frenchman long ago--but he included it in his book about graphs because it is damn near perfect and conveys such a startling amount of information. Such as "Never get involved in land war in Asia!" (In winter, too, I might add).