Three Data Dimensions
It is rare to see 3D used in statistical graphics to really depict three data dimensions, but in this infoporn by Arno Ghelfi for Wired Magazine it is done brilliantly: You can see the device price of selected consumer electronic goods over time and the market penetration of the device in question. It is always beautiful to have these long running timeseries but this one is very close to a geek's heart. Early adopters paying high prices as the latest gadgets become available and over time these devices become mainstream as their price drops. There is also a lesson to be learned here as some products like DVD players become drastically cheaper as they approach their end of life cycle. Only the PC is different compared to the other items in that its price didn't drop that dramatically despite its growing market penetration.
This is one of the many great examples that are showcased in Visual Language for Designers: Principles for Creating Graphics that People Understand, a recently published book by Connie Malamed that does a lot more than showcasing best practices without discussing bad examples:
Malamed is a cognitive scientist, artist, and educator. As such, she recognizes the need for infographics to be designed with an understanding of what actually works, based on empirical research. She proposes design principles that have emerged from an understanding of how the eyes and mind function, drawn from research in the fields of visual communication and graphic design, learning theory and instructional design, cognitive psychology and neuroscience, and information visualization.Stephen Few: At Last, a Scientific Approach to Infographics, review.