Being the gamers we are, I suggest heading over to Microsoft's excellent Halo 3 website, a terrific demonstration of the power of Silverlight.
Silverlight is Microsoft's newest platform for rich UI development. Similar to Flash, Silverlight is cross-browser compatible, has a very lean installer, and is incredibly powerful.
You'll find more examples of Silverlight work at Silverlight's official website. Here at Appian, we are excited about the new possibilities this new technology brings to the web, and are beginning to experiment with it now. Imagine the possibilities!