I am evaluating Adobe Flex [1] technology to do rich internet [2] applications. Sometimes a picture is worth a thousand words: so in the following I sketched an overview of Flex programming capabilities.
Diagram focuses on how to create a Flash Application (compiling MXML [3] and Actionscript [4] files using the free Flex SDK [5]) and on what kind of interactions a Flex-made application can perform with external systems.

Some starting (and incomplete) references:
[Source: Piero Campanelli [11]]
Links:
[1] http://www.adobe.com/products/flex/
[2] http://en.wikipedia.org/wiki/Rich_Internet_application
[3] http://en.wikipedia.org/wiki/MXML
[4] http://en.wikipedia.org/wiki/Actionscript
[5] http://www.adobe.com/products/flex/sdk/
[6] http://en.wikipedia.org/wiki/Action_Message_Format
[7] http://en.wikipedia.org/wiki/Real_Time_Messaging_Protocol
[8] http://www.adobe.com/products/flex/dataservices/
[9] http://www.openamf.com/cms/
[10] http://osflash.org/red5
[11] http://www.pierocampanelli.info/technology/2008/01/20/a-sketch-of-adobe-flex-architecture-capabilities/