If you are looking forward to develop rich web 2.0 applications then Dojo Foundation has come up with 1.0 version of open source JavaScript toolkit for Ajax development. The toolkit consists of Dojo Core, Dijit rich user interface controls and DojoX component offering vector graphics, charting and community extensions to Dojo. Its all loaded with full library of UI controls, universal data access for widget development, CSS-driven which makes customization and extension a lot simpler and what else there is another component called Dojo Offline using which you will be able to build offline applications. So just go ahead and build your dream applications!!