http://www.edwardtufte.com/tufte/ http://www.edwardtufte.com/tufte/ http://www.perceptualedge.com/ http://www.perceptualedge.com/ I've read books by both thes

http://www.edwardtufte.com/tufte/ http://www.edwardtufte.com/tufte/ http://www.perceptualedge.com/ http://www.perceptualedge.com/ I've read books by both these authors and they were very good. Their websites cover most of the important content found in the books.