Best sample app for learning best practices, OO & asp.net?

[karim]

I have a programmer that wants to learn asp.net(c#) and best practices for
coding styles, OO and ease of maintenance. What's the best sample
application out there that is a very good source for learning? I am aware
of these apps:

- Quickstart apps at asp.net
- Pet Store app
- Fetch & Mather
- ...?

Karim