YUI

I was playing with YUI recently. YUI is not only three consequential buttons on the keyboard, it's a Yahoo UI library, fully JavaScript driven. It's similar to Dojo where you can have all the kind of UI elements such as tabbed panes, dialogs, layouts, tables and trees.

It's really nice an could be a very good base for "second generation AJAX" applications. Applications where data is delivered from the server via Async XML HTTP Request (and most probably JSON) and rendered by Javascript. The main difference from "classical AJAX" is that we are not sending HTML from server just to do a partial request, but client application has a notion of "model" and "view" rendered by Javascript.

The main difference of YUI to other frameworks are mainly huge user base, excellent documentation, huge number of examples and high quality you can expect from company like Yahoo.