javascript/ajax:

Witty  (also) Wt (wit-ty) is a Web Toolkit. It provides a C++ interface for building a web application, that resembles existing application user interface APIs.

ATLAS “Atlas” makes it possible to easily take advantage of AJAX techniques on the Web and enables you to create ASP.NET pages with a rich, responsive UI and server communication.

Oracle's AJAX Framework [slashdot.org]... 

Eclipse AJAX Toolkit Framework [eclipse.org], which uses Dojo [dojotoolkit.org], 

Zimbra [zimbra.com], and OpenRico [openrico.org] (which in turn uses prototype [conio.net])...

Dojo, the javascript toolkit. Dojo is an Open Source DHTML toolkit written in JavaScript. It builds on several contributed code bases (nWidgets, Burstlib, f(m)), which is why we refer to it sometimes as a "unified" toolkit.

ZK, ajax but no javascript web framework.  ZK is an open-source Ajax Web framework that enables rich UI for Web applications with no JavaScript and little programming. With event-driven feature-rich components, developing becomes as simple as programming desktops. With a markup language, designing becomes as simple as authoring HTML.

GWT, Google web ajax toolkit. (slashdot) (java to javascript compiler). You write your front end in the Java programming language, and the GWT compiler converts your Java classes to browser-compliant JavaScript and HTML. (limitations: 1)

YUI, Yahoo UI library (slashdot) (java script include). To use a specific component from the YUI Library, include the path to that library in a <script> tag within your web page.

Prototype (java script include) Prototype is a JavaScript framework that aims to ease development of dynamic web applications.

Scriptaculous java script library for visual effects. 

Helper module for Ruby on Rails  Provides functionality for working with JavaScript in your views.  

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate.

Echo Framework  (demo) Echo2 removes the developer from having to think in terms of "page-based" applications and enables him/her to develop applications using the conventional object-oriented and event-driven paradigm for user interface development. Knowledge of HTML, HTTP, and JavaScript is not required. Applications may be hosted using any Java servlet container. Echo2, like its predecessor, is open-source software distributed under the terms of the Mozilla Public License (or, if preferred, the GNU LGPL License).

ThinWire

LISP to javascript

java:

Eclipse, Java IDE.