SandCastle produces MSDN style documentation of your code by reading your XML Comment Tags and other information (an upgrade to the features the old tool provided). Here's the overview from the download site and a link to download it.
From Microsoft Downloads:
Sandcastle produces accurate, MSDN style, comprehensive documentation by reflecting over the source assemblies and optionally integrating XML Documentation Comments. Sandcastle has the following key features:
~ Robert Shelton