Scriptaculous

Scriptaculous provides you with all the necessary elements to create several animations and effects that, until recently, were only possible with Flash or similar programs.

Use the drag and drop feature, change an element’s style properties by accessing them directly from javascript, and more, all without ever having to reload the entire page thanks to the Ajax functions provided.

In order to use this library, you’ll just have to add two includes on your html, one to the page containing the javascript functions, and another to the stylesheet you want to use. Plus, since Scriptaculous comes with the prototype library, you’ll be able to convert static divs into windows with many different looks thanks to the style sheets mentioned earlier.

If you want to start a web 2.0 project, then this is the most direct and complete way to get started.