Tufte has authored several more books that expand and illuminate these themes of quality and effectiveness in graphical communication. All of the books are beautifully printed. Tufte also teaches seminars and maintains a web site at: http://www.edwardtufte.com/tufte/
Another work I have found very useful is “Information Dashboard Design” by Stephen Few (ISBN-0596100167). This book applies visual communication principles from Few, Tufte and other researchers to the practical application of “dashboard design” . Few’s book analyzes the shortcomings of some poor designs and then goes on to enumerate a number of elements for effective designs. He closes the book with some examples of optimal designs.
Stephen Few also teaches public workshops. His schedule and blog can be found at http://www.perceptualedge.com/.
Lastly, the IBM Many Eyes project http://manyeyes.alphaworks.ibm.com/ is an ongoing source of inspiration and amusement.