The seminar today was just excellent. On his site I found the following article which I haven’t yet read. But, based on the pictures alone, I know I’m going to like it. Tufte is a big proponent of “Put the data IN the chart” rather than using a legend. This is illustrated here.
Postscript: Ann points out that when she learned GANTT charting in grad school, it was with the data in the chart.