Axiis, an open source data visualization framework in Flex, was released a few days ago under an MIT license. I haven't done much in Flex, but from what I hear, it's relatively easy to pick up. You get a lot of bang out of a few lines of code. Axiis makes things even easier, and provides visualization outside the built in Flex graph packages.
Axiis gives developers the ability to expressively define their data visualizations through concise and intuitive markup. Axiis has been designed with a specific focus on elegant code, where your code can be just as beautiful as your visual output.
Above is the wedge stack graph. Here's your standard area graphs:
See what other visualizations you can create with Axiis here.
Visualization Toolbox Continues to Grow