Code Camp Server is a nice reference for ASP.NET MVC and NHibernate
http://codecampserver.codeplex.com/
Also, read a book on the subjects. It will help you a long way.
Edit:
You seem to be looking for a general guide, to take you through some concepts of good design etc. Specifically for ASP.NET MVC, I can recommend http://jeffreypalermo.com/blog/read-all-of-asp-net-mvc-2-in-action-now-while-you-wait-for-the-printed-book/
You mention Onion architecture, the book was written by Jeffrey Palermo, who (AFAIK) invented the term.
If you'd like more sample projects (there are lots and lots) of ASP.NET MVC (with or without NH), let me know.