This extension allows you to build NuGet packages within the Visual Studio IDE, right along with your other projects. It creates a new .nuproj project type in Visual Studio and a MSBuild-based build system for creating .nupkg files from .nuspec files. It only requires that you have NuGet installed.
Check out the source and readme at http://github.com/bspell1/NuBuild. Please send any feedback or issues to email@example.com.