The Map used a variant of the "treemap" technique pioneered by Ben Shneiderman. The screen is divided into rectangular tiles that represent publicly traded companies. The area of a rectangle corresponds to the market capitalization of the company, and the color tells you how the stock price has changed since the previous market close. Unlike a traditional treemap, however, the Map of the Market introduced a new algorithm designed to create tiles that were close to square, making for a display that is more legible and easier to interact with. (It turns out that several others, including Jarke van Wijk, independently invented similar algorithms around the same time.)

The Map of the Market quickly became one of the most trafficked sections of the site, and spawned many imitators. Today treemaps are a standard tool for visualizing financial data.

At SmartMoney we created many variations of this map. One of my favorites the site History Wired, a visualization of a selection of objects from the Smithsonian Museum. This was built in collaboration with Judy Gradwohl at the Smithsonian.