I came across this really cool Javascript Framework yesterday. The framework is a little different from the other common ones (YUI, ExtJS, JQuery etc). While it does all the normal things such get AJAX calls, DOM abstraction, Event management, it also does some other things that I have never seen before. There is a pivot table, SQL query designer, database designer, vector graphics drawing facilities, drag-and-drop lines (and curves!).

The framework is unfortunately quite complex and the documentation is scant.

OAT Javascript Framework: http://oat.openlinksw.com