Build Projects and Solutions from Windows Explorer with MSBuild 4.0

Copy the following into a .reg file and run. This will give you the ability to Build, Clean, and Rebuild from the Windows Explorer Context menu.

Windows Registry Editor Version 5.00 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell\Build] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell\Build\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:build\"" 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell\Clean] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell\Clean\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:clean\""

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell\Rebuild] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.sln\shell\Rebuild\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:rebuild\""

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell\Build] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell\Build\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:build\""

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell\Clean] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell\Clean\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:clean\""

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell\Rebuild] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.csproj\shell\Rebuild\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:rebuild\""

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell\Build] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell\Build\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:build\""

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell\Clean] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell\Clean\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:clean\""
[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell\Rebuild] 

[HKEY_CLASSES_ROOT\SystemFileAssociations\.vbproj\shell\Rebuild\command] 
@="cmd.exe /K \"\"%%windir%%\\Microsoft.NET\\Framework\\v4.0.30319\\MSBuild.exe\" \"%1\" /t:rebuild\""

For more advanced control, try the MSBuild Launch Pad on Codeplex.