Turning the Pages 2.0 is an amazing example of what can be done with WPF and Silverlight. Using a high-end scanning device, the British Library has taken a number of precious books, which you would normally only be able to see under glass, and open to a single page chosen by a curator, and allowed the public to view the entirety of these books, using the familiar notion of turning the pages.
The Silverlight version (above) allows you to choose from 5 of the library's treasures, and flip through them page by page. You can also rotate the book to view illustrations that are printed horizontally, zoom in or out, and move the book for a better view.
The Windows Presentation Foundation version (requires Windows Vista) adds several very cool features, including a magnifier for looking at fine details, and the ability to move the book in three dimensions.
All-in-all a very cool use of technology, and an opportunity to see more of some historic treasures than would ever have been possible without it.