I'm working on a little project to satisfy my idea on creating a mapping for NHibernate describing the model entities in a notepad like fashion. The application I created leverage a new SDK from microsof, at present in CTP: Microsoft Oslo SDK.
The application starts from a very simple language, and starting from this creates the clsses, the hbm's and the database script ( Database script at the moment does not work... ;)
). The application deal with collections,references, subclassing, and many-to-many relationship.
Lets have a couple of screenshot, the first one about a relation Books-Authors...
This is the hbm (whit all the mapping in a single view ):

and this the mapping ( all the classes in a view):

A sample with subclassing ( a just for fun financial model )
Well, there is still some bugs, but the application really do what expected: a lot of boring code line autogenerated from an intuitive textual DSL.