Do you want to start developing ? There are a lot of alternatives. All with diferent pros and cons. For all platforms. Free and expensive. Here I will enumerate the most popular.
Is not finished, I will keep adding more frameworks and resources.
OpenLaszlo programs are written in XML and JavaScript and transparently compiled to Flash and, with OpenLaszlo 4, DHTML. The OpenLaszlo APIs provide animation, layout, data binding, server communication, and declarative UI. An OpenLaszlo application can be as short as a single source file, or factored into multiple files that define reusable classes and libraries.
Create a database-driven, ready-to-extend application in minutes. All with designer friendly templates, easy AJAX on the browser side and on the server side, not a single SQL query in sight with code that is as natural as writing a function.
Based on the python scripting language.
Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design.
Grails aims to bring the "coding by convention" paradigm to Groovy. It's an open-source web application framework that leverages the Groovy language and complements Java Web development. You can use Grails as a standalone development environment that hides all configuration details or integrate your Java business logic. Grails aims to make development as simple as possible and hence should appeal to a wide range of developers not just those from the Java community. Below you can find all you need to know (and more) about Grails.