http://silverlight.live.com (Microsoft Silverlight Streaming) is a free service from Microsoft to host your Silverlight applications and videos. You can upload your .xap or .wmv files and reference them from any websites, blogs, etc. My favorite part is that you get 10 GB in free storage, with no ads, no strings attached. Also, they give you high scalability and availability – the media is hosted “in the cloud” that can handle a lot of traffic. Finally, you have a nice admin site where you can manage your account, videos and applications – you can upload new videos, applications, track usage (number of downloads or video views), etc.
The MSDN Silverlight Streaming Samples page contains several nice Silverlight samples. I use http://silverlight.live.com to host http://livegeometry.com and my other applications and videos. Enjoy!