There is a very good library of UI functionality coming with JQuery, the famous JavaScript library. The UI reference can be found here.

Giving an extream power to use the user interface on it’s limits, with functionalities as drag and drop, resize, select, sort, etc.

This subset of the JQuery library can be used with very small code includes, and that makes the ease of use even more. Actually I think that library is really more easy to use than any other as SPRY, YUI, etc.

I recommend it!