NullObject.For<T> - As simple as it gets, but no simpler
This NullObject Factory from Paul is very nice, simple and clean in its design. I really like it and I can see many uses for it, in parallel with working with your standard mocking framework or IoC Container Implementation.
here is a little usage example (last line):
var controller = new AccountController( // Class I am testing
mockCustomerRepository, // Class I am mocking
NullObject.For<ILogger>()); // Who cares about logging!