The Visual LINQ Query Builder is a Visual Studio 2008 Add-In and designer that helps you create LINQ to SQL Queries in your application.
Per Mitsu's Blog:
“Once Visual Linq Query Builder is installed, you can create a new project or open an existing project (C# or VB.Net). From this designer you will be able to create, modify and delete queries. When editing a query, the query designer will appear and let you build your query visually. At each time the designer is saved, the corresponding code (C# or VB.Net) will be generated. Then the queries are ready to be used by your project. The following steps are for the first time users of Visual Linq Query Builder.”
You can find Visual LINQ Query Builder on Code Gallery.
You may also want to look at LINQPad: LINQPad - Dynamically Query SQL Server Databases in LINQ