Scott Hanselman did an interesting session at MIX09 called "File|New -> Company", where he essentially started with a blank screen, and using Visual Studio, ASP.NET, Ajax, and Model View Controller he created an entire website called "NerdDinner.com",
which is a social networking sites for... well... nerds, to allow them to coordinate with their friends what restaurants to go to and what to eat.
While we didn't have time in this episode to let Scott repeat this feat, we did get a chance to talk with him about how the various technologies he utilized worked with the tools in order to make it possible.
If you really want to see him take on this challenge, you can watch his session from MIX09:
And if you want more details about Scott, NerdDinner.com or Model View Controller, here are some additional links: