This visualization from Yahoo research is very interesting. I attended a talk at eTech where the speaker diss’ed the famous Minard’s Napoleon’s advance graph saying "but it didn’t help Napoleon make a single decision." The audience of course vehemently protested, echoing Tufte in a manner like Trekkies quote Spoc, "but it wasn’t designed for that! It was a antiwar protest poster!"
Reading the comments on the digg story, the best part is the link to the paper explaining the technique used. Data mining such a large time sensitive data set is not easy. I like the fact they explained how they did it.