The SeaMonkey project is a community effort to develop an all-in-one Internet application suite. It contains an Internet browser, email and newsgroup client with an included Web feed reader, HTML editor, IRC chat, and Web development tools, and is sure to appeal to advanced users, Web developers, and corporate users. It uses much of the Mozilla source code powering such successful siblings as Firefox, Thunderbird, Camino, Sunbird, and Miro.
Dojo is a cross-browser AJAX/DHTML toolkit for building dynamic Web UIs. Dojo includes a rich-text editing component, an aspect-oriented event system, rich drag-and-drop support, a rapid-prototyping framework for building new widgets, and a full-featured abstraction for XmlHTTP I/O. In short, it's a very fast way to build Web interfaces.
GWTruts is an easy-to-use framework for using GWT with MVC and dependecy injection. It virtually divides a GWT module into view, controller, and validation sections similar to traditional MVC Web frameworks like Apache Struts. It also provides a dependency injection mechanism similar to Spring, which you can use to customize your controllers and views. It provides a page decorator where you can define mappings between a URL and a group of controllers/views and sections of the HTML files.