ActiveWidgets – Javascript library
Here’s a cool set of Javascript Widgets, unfortunately the library is not free, but a good place to see what Javascript can actually acomplish on the client side. 
ActiveWidgets is a powerful javascript component library which makes web application development (especially AJAX-style apps) a lot easier and more productive. ActiveWidgets provides you with a set of common visual elements (like datagrid, tabs, tree, combo) sharing professional look-and-feel and simple programming model.
Link: ActiveWidgets • Ajax Grid • #1 Javascript Datagrid Control and Component Library.
