Visual LINQ Query Builder
Soups up! 
Visual LINQ Query Builder
http://code.msdn.microsoft.com/vlinq
Visual LINQ Query Builder is an add-in to Visual Studio 2008 Designer that helps you visually build LINQ to SQL queries. Functionally it provides the same experience as, for instance the Microsoft Access Query Builder, but in the LINQ domain. The entire UI of this add-in uses Windows Presentation Foundation. The goal of this tool is to help users become more familiar with the LINQ syntax.
It's also a project that could help you to see how to create your own Visual Studio 2008 add-in using Windows Presentation Foundation.
Requirements
You will need to have Visual Studio 2008 installed. You can use the Visual LINQ Query Builder in any kind of project that supports LINQ to SQL.
Visual LINQ Query Builder is only supported with C# and VB.Net projects.