The Stanford Alumni has a great overview of Edward Tufte's work (written by Fran Smith). Some excerpts:
As Tufte sees it, what makes evidence beautiful isn’t artistry. “It’s all about discovering and telling the truth,’’ he says. (...) AFTER AN ENCOUNTER with Tufte’s ideas, people can never again look at a chart, a map, a scientific table or a PowerPoint presentation quite the same way (...) Like the earlier books, Beautiful Evidence isn’t an instruction guide but a statement of Tufte’s design principles: Show comparisons. Show causality. Show data in their full complexity. Document and display your sources. Above all, respect the intelligence of your audience and tell the truth. “Serious presentations,’’ Tufte often says, “rise and fall on the quality, relevance and integrity of the content.’’ (...) it’s not a single image that makes Tufte’s work memorable; it’s the mix and multitude.