Microsoft Live Labs technology that helps to explore the web which you have never done before. Pivot Viewer to view relationships between “collections” of individual information on the the web, slice and dice it to see the results in no time.
The more features can be explore by this link to Microsoft Pivot viewer website.
The Power Pivot, a BI tool to be used with the Microsoft Excel to explore the data visually is also a powerful tool provided Free by Microsoft.
Another data visualization tool is Tableau Software Public edition for the website data.
For more details and download Tableau Public