Developing rich internet apps - what to use

A quick round up of what seem to be the current major development libraries and/or environments for developing RIAs.

Flash is the well-known browser plug-in from Adobe as well as the development platform. Adobe have also announced in the mean time - but not released - Apollo as a cross platform run-time that handles Flash, Flex, PDF, plain HTML or Ajax based user interface. Effectively a type of universal client instead of the browser.

DoJo is an open source javascript library. As well as the usual UI components, one feature I find interesting are components to store data on the local drive. I first saw this feature used in TiddlyWiki.

script.aculo.us is also a javascript library. It is based on the Prototype javascript library.

Google Web Toolkit (GWT). The GWT lets developers write code in Java which is then converted to JavaScript apparently apparently freeing the developer for learning JavaScript (Java developers are assumed here, not a bad assumption for most enterprise development work). This has been nicely written up in a IBM developer world article.

Are there any more?