I was only thinking the other day, "Wouldn't it be great if someone wrote an add-in to Visual Studio that let you drag tables from a database and it generated NHibernate-compatible class definitions and mapping for me".

Well it appears I wasn't the first to have this idea.

The project seems to be run by Adam Langley. There is some source code available, though not in the SourceForge SVN/CVS repository.

One problem at the moment is that it only generates C# code.