The concept of heat map graphics works very well for stock market dashboards. See this one in action when the nasdaq is open and go here for the underlying technology.

This is an animated gif:

This is a screenshot of the one on the exchange:

So what or who is The Dashboard Spy? As his about page states, The Dashboard Spy is just a guy interested in the design of business dashboards. He could not find any executive dashboard design source books and so set about creating his own. Finally convinced to post his extensive collection of dashboard screenshots online, he was amazed to find how popular it has become. If you have a nice screenshot of an enterprise dashboard, balanced scorecard, or any business intelligence graphic to share, please send an email to info _at_ dashboardspy.com. Also check out The Dashboard Spy’s favorite books.