ASP.NET Authentication for Silverlight Applications (Accessing ASP.NET Membership, Profile and Role Services)
This is very good for web sites that have ASP.NET Authentication (or plan to have) and have Silverlight apps.
Brad Abrams, from his blog:
"Here is what I plan to show:
2. Save personalization settings
3. Enable custom UI based on a user's role (for example, manager or employee)
4. A custom log-in control to make the UI a bit cleaner
Source code available on the above post.