I want to know the must-have helper classes to make an MVC application as decoupled as possible without being ridiculous. Below I am listing the helper classes available from the NerdDinner.com ASP.net sample application showing off MVC Framework.
- ControllerHelpers.cs
 - FileNotFoundResult.cs
 - HandleErrorWithELMAHAttribute.cs
 - MobileCapableWebFormViewEngine.cs
 - PaginatedList.cs
 - PhoneValidator.cs
 - UrlHelperExtensions.cs
 - SessionHelper.cs (not in NerdDinner)
 
Also I usually include a few htmlHelpers, and for sure Interfaces for my datasources, but that is not a helper I guess.
Thanks.