Clare recently mentioned that Jesper Johansson, an exceptional Microsoft Security Technology presenter, attended a Presentation Skills course. What she didn't mention is that it was Dr Edward A Tufte's course on presenting quantitative information.
If you present or visualize information at all - in the context of PowerPoint slides, user interface design, reports pulled out of SQL Server, or wherever else - you need his books on your shelf. Actually, if you visualize information, you probably already have his books on your shelf, and I seem to recall saying the same a while back!
I loved reading Jesper's thoughts on the course, his discussion of Tufte's explicit and implicit messages, and his emphasis on the difference between giving a speech and presenting. Jesper, you lucky guy :)
If I can take this discussion from Presentation Skills to UI for a sec, I often hear it said that with Avalon's great power will come great responsibility for user interface designers. (Think 'blinky-text-on-early-web-pages.') The elegant, simple, information-rich aesthetic that Tufte advocates will enable designers to use Avalon's power for good, or for awesome.
Some great Tufte stuff for the uninitiated in poster form: Napoleon's March (his nod for possibly the best statistical graphic ever drawn); the Historic Visual Diary of Spaceflight, handmade by a Russian comonaut; the Cognitive Style of PowerPoint, in Stalin Sqare style.
[Humble Addendum redux: When I was finishing my Master’s thesis on computer learning, I drew great inspiration from Tufte's books when I was trying to visualize different representations in the architecture. However, there’s a big gap between believing in his design principles and being capable of applying them – and I freely admit that he's given me a lot to aspire to ;) ]