The XEO (eXtensible Enterprise Objects) Framework is an agile development framework designed to create enterprise web applications. XEO is built around Object Oriented concepts, Model Driven Development (MDD), Model View Controller (MVC) and Model Driven Architecture (MDA) and it's powered by Java.
Æjaks combines the server-side Ajax windowing system Echo2 with the powerful simplicity of the Tcl langauge. The result is a rich development environment in which to develop Ajax-based web applications, often with much less code to write. Æjaks runs on top of a Java Servlet engine, and can make use of any existing Java library.
Aero is a PHP5 framework with a highly modular design, intended for programmers who prefer to control every aspect of the application they build. Unlike many other frameworks Aero does not make any decisions for you, there are very few conventions or rules you should follow.
Agavi is a powerful, scalable PHP5 application framework that follows the MVC paradigm. It enables developers to write clean, maintainable and extensible code. Agavi puts choice and freedom over limiting conventions, and focuses on sustained quality rather than short-sighted decisions.
AgileUnit is a small framework developed to increase the feedback loop while developing applications. Get feedbacks from your app while your customer is using it. Figure out what your customer really want early, which functions are most used and which not. Merge synergy of requirement, development, testing and maintenance to one piece.
AIDA/Web is a Smalltalk web application framework for building complex web applications with integrated Ajax support, rich collection of web components to build web pages programatically, MVC-like separation of presentation from domain, REST-like nice looking and bookmarkable url links, with integrated session and security management, a Swazoo web server and many more.