Edward Tufte is the writer of such classic books as The Visual Display of Quantitive Information. He has become justifiably known for writing very lucidly on how, and how not, to present information visually.
I was sitting in a bar with a co-worker when we started talking about graphs. I asked him: "Do you know that graph showing the progress of Napoleon's invasion into Russia?" to which he immediately replied: "Yes! That's awesome!" And it is, see for yourself. I learned of this graph by reading The Visual Display of Quantitive Information, and I suspect many other people did as well. Not only it is a wonderful graph, it also leads to good conversations in bars.
But anyway, Mr. Tufte has started something between a blog and a bulletin board. Basically, you can ask him a question, and then he and other readers may answer. You can also read this part of the site using an RSS reader. So far, all of the entries have been quite interesting. My favorites are on user testing (Mr. Tufte gives some very good arguments against user testing in his particular situation), what Richard Feynman has said about teaching (which is really about creativity) and the origins of the London Underground Map (from which I learned that it took decades to make, and that someone wrote a book about how it was designed).