My open-source MyNHibernateContrib project, which adds support for generics, two-way collections and nullables to NHibernate, finally got a decent example web app. It is very small (as good example apps should be), just large enough to demo each feature.
I still hope that the NHibernate community will integrate this library into NHibernateContrib's .NET 2.0 version once they start one. Of course, if they add support for these features directly into NH itself, I'll be more than happy to retire my library.
The generic, two-way collection coding pattern when using this library has improved from several months ago, but it still requires a few lines of plumbing code that's not the most intuitive. Copy and paste from the example app. And if you know a better way to make it work, please let me know!