Check out the walkthroughs and demos from Ian Morrish's site: SharePoint Silverlight Demo
Silverlight BluePrint for SharePoint
Another nice explanation of creating Silverlight applications for SharePoint in VS using the extensions can be seen on Andrew Whitechapel's blog.
Saurabhd Dasgupta works for Microsoft Consulting Services and posted these great articles:
An approach towards implementing information entry forms using Silverlight and SharePoint Part 1 and Part 2.
How to Create a Silverlight Web Part in ASP.NET for Use in SharePoint Server 2007
Silverlight webpart for SharePoint by Shantha Kumar
Simon's BinaryJam Silverlight Photoviewer Web Part
Kirk Evan's Hosting Silverlight in a SharePoint Webpart
Randy Williams: Tips For Writing Silverlight Web Parts in SharePoint: Part 2
Tips For Writing Silverlight Web Parts in SharePoint: Part 1
Silverlight Web Part in SharePoint