UxMag

Theresa Neil published a useful catalog of data visualization/charting toolkits for a number of Web application frameworks on O'Reilly's InsideRIA:

http://www.insideria.com/2009/12/28-rich-data-visualization-too.html

Since data is only a powerful tool if people can readily use and respond to it, this list is really handy. It's good to see so many open source toolkits, too.