All around the web it’s very easy to find different ways to link Arduino to a wide range of apps, like Processing, VVVV, Pure Data, Quarzt Composer and so on.
Have a look at this screencast to check hot to drive Arduino via Adobe Flex.
I made a 20 minute screencast on a little project I made this weekend. It is a volume meter that reacts to MP3’s playing in a Flex app. In its entirely, the entire project is very simple — 4 LEDS connected to the Arduino, and a 50 line Flex 4 application which controls them. I’d like to say that there was a hard part to this, but thanks to Justin Mclean’s class, there really wasn’t one. You can download the Flex source-code to the app here (but you will have to supply your own MP3 to play in the assets folder).