Scott Guthrie one of my favorite Microsoft employees, provides us with his insight into not only the new Visual Studio, but also the new features of the .NET languages. In his blog series this summer he has been discussing LINQ which is an overall querying programming model.
His most recent blog post, found here, discusses and an add-in to the new Visual Studio 2008 which can be downloaded from his post. This add-in allows the visual debugging and testing of your LINQ statements in your code.
If your interested in LINQ this is a must to take a look at.