Below are a list of must have Visual Studio Tools. They are all free and from Microsoft!
Visual Studio 2010 Feature Packs http://msdn.microsoft.com/en-us/vstudio/ff655021.aspx
Feature Packs enable you to extend Visual Studio 2010 with capabilities that enhance and complement the existing tools.
Visual Studio 2010 Feature Pack 2 (MSDN Subscribers Only) Cumulative feature pack that extends testing, code visualization and modeling capabilities in Visual Studio 2010.
Use Microsoft Test Manager to capture and playback action recordings for Silverlight 4 applications.
Create coded UI tests for Silverlight 4 applications with Visual Studio 2010 Premium or Visual Studio 2010 Ultimate.
Edit coded UI tests using a graphical editor with Visual Studio 2010 Premium or Visual Studio 2010 Ultimate.
Use action recordings to fast forward through manual tests that need to support Mozilla Firefox 3.5 and 3.6.
Run coded UI tests for web applications using Mozilla Firefox 3.5 and 3.6 with Microsoft Visual Studio 2010 Premium or Visual Studio 2010 Ultimate.
Code visualization and modeling features (requires Visual Studio 2010 Ultimate):
Use the Generate Code command to generate skeleton code from elements on UML class diagrams. You can use the default transformations, or you can write custom transformations to translate UML types into code.
Create UML class diagrams from existing code.
Explore the organization and relationships in C, C++, and ASP.NET projects by generating dependency graphs.
Import elements from UML sequence diagrams, class diagrams, and use case diagrams as XMI 2.1 files that are exported from other modeling tools.
Create links and view links from work items to model elements.
Create layer diagrams from C or C++ code and validate dependencies.
Write code to modify layer diagrams and to validate code against layer diagrams.
Productivity Power Tools http://visualstudiogallery.msdn.microsoft.com/en-us/d0d33361-18e2-46c0-8ff2-4adea1e34fef
A set of extensions to Visual Studio Professional (and above) which improves developer productivity. In this third major release of the Power Tools we have made significant improvements to the Solution Navigator and the Tab Well to address our top customer requests.
PowerCommands for Visual Studio 2010 http://visualstudiogallery.msdn.microsoft.com/en-us/e5f41ad9-4edc-4912-bca3-91147db95b99
PowerCommands 10.0 is a set of useful extensions for the Visual Studio 2010 adding additional functionality to various areas of the IDE. Visit the VSX Developer Center at http://msdn.com/vsx for more information about extending Visual Studio.