Stackoverflow

stackoverflow.com is an asp.net site built on top of asp.net MVC application and allows the user to post questions without actually registering. Registration is only required if you want to answer a question.

from the interview with scott hanselman podcast-

what makes it interesting for any one planning to build a new idea is -
1. The entire application is deployed on one IIS machine / sql server (on same machine).
2. The development is done on the same production machine :0

WhatI like about this is ,you dont need to spend big for a startup or follow all the best practices, if you have some idea ,go ahead and built it first and quick!!

And also nice to know that asp.net MVC framework is maturing with all these apps ...

-Sree