SilverlightExcel is a Silverlight application allowing you to open and view Excel files and also create graphs.
Let’s imagine a scenario in which you have a series of Excel files (.xlsx) on your computer but you don’t have any Microsoft Office installed.
This small application is designed to allow you to view Excel files and create simple charts.
In this article http://www.silverlightshow.net/items/An-Excel-file-Viewer-in-Silverlight-4.aspx
you can find a complete description of the project.