Microsoft has a new documentation tool coming called Sandcastle. Sandcastle creates MSDN like documentation by reflecting over your assemblies and optionally integrating your authored XML documentation.
Sandcastle appears to be a replacement for NDoc. This is a good thing, because NDoc has apparently been in a state of limbo for awhile. There was some limited 2.0 Framework support and someone else added some additional support that isn't available on the SourceForge website, but for the most part its future is unclear.
Sandcastle should be a great tool, because according to the blog “[it] is used internally to build .Net Framework documentation.” And therefore will give us consistent looking documentation.