Glad you like it...
Warning: now you've encouraged me.
This one is an interesting view of the historical returns of the S&P 500:
Many Eyes: Sand P 500
We're all familiar with stock charts, which showing price over time in the shape of a line graph. This application shows the S&P 500 value over about 12 years ending in 2007.
The display is interesting because it's made up of a stack of 500 line graphs. But the really cool part is you can use your mouse to dynamically rearrange the members of the dataset by sector, subsector or by stock, to see trends by industry. The dot-com bubble is clearly visible.
On the left side, there's a check box that allows you to drill down into those same subsets to see how, for example, the integrated oil gas companies and that subgroup's individual stocks of the have done over time.