Need Sample Projects in HTML 5 ?

You can have any of your ASP.Net web applications use HTML5. All you have to do, is to add the doctype declaration

This can be added to your master page itself.


After this, you can add/use html5 controls/features to any page. 
All you have to remember to do, is to catch and handle cases where the client browser does not support html5.


Here is some more reference info:
HTML5 support in Visual Studio 2010
ASP.Net MVC 3 HTML5 helper
Sample Application NerdDinner (uses ASP.Net MVC and html5)
 Cheers!