While Visual Studio 2010 certainly contains an excellent set of tools for the SharePoint 2010 developer, both Microsoft and the community at large are constantly providing you with further excellent sample code, utilities, and productivity aids. In this section, I recommend three key tools that you should have, and will direct you to a location where you can find more!
Here is the recipe for installing key SharePoint developer tools:
Mandatory for all SharePoint developers is the SharePoint 2010 SDK that includes many code samples and documentation. Use your favorite search engine to find Microsoft SharePoint 2010 SDK.
Highly recommended is the SharePoint Guidance available at http://www.microsoft.com/spg, with additional information available at http://spg.codeplex.com.
Highly recommended is the Community Kit for SharePoint. It is a set of best practices, templates, Web Parts, tools, and source code that enables practically anyone to create a community website based on SharePoint technology for practically any group of people with a common interest. It is available from http://cks.codeplex.com.
Highly recommended is the SharePoint Manager 2010 tool. It is a SharePoint object model explorer that enables you to browse every site on the local farm and view / change every property. It is from http://spm.codeplex.com.
Suggested are the Visual Studio 2010 SharePoint Power Tools, especially if you plan to develop Sandboxed Solutions . Use your favorite search engine to find Visual Studio 2010 SharePoint Power Tools.
You have successfully installed the key tools every SharePoint developer should have at hand.
There are far too many excellent tools contributed by the community to be mentioned here, and more being created all the time. Some will be useful to accelerate some very specific development task. The primary source is CodePlex at http://www.codeplex.com. Search the site for SharePoint 2010, or more generally, SharePoint (as some tools support both the current and older versions of SharePoint).