Microsoft PivotViewer is a really cool Silverlight web-based control that provides a visual way to interact with massive amounts of data (download).  It allows you to present thousands of things at once and visualize them in a way that exposes value from the group.  By visualizing thousands of related items at once, users can see trends and patterns that would be hidden when looking at one item at a time.  Which makes it ideal as a business intelligence reporting tool.

To build a PowerViewer app requires Visual Studio 2010, Silverlight Tools, and the PivotViewer SDK.  You will create a Silverlight project in Visual Studio, add a reference to the PowerViewer control, and off you go!  There is also a PivotViewer Extension for Reporting Services.

A great example of seeing this in action is this cool application that allows you to sort thru all the sessions for PASS Summit 2012.  Also check out Netflix Instant Watch collection, Top SharePoint Internet Sites,

More info:

PivotViewer

Lessons in PivotViewer

Quick Steps to displaying data using PivotViewer and Silverlight

Hacking PivotViewer