If you use ReSharper or think you might someday, you owe it to yourself to check out Ilya Ryzhenkov’s ReSharper blog. Ilya is one of the ReSharper developers, and he’s also one of the foremost “ReSharper Jedi” — think power users with light sabers.
I just picked up a sweet trick reading his “Jedi Way — Implementing Members” post: if you’re adding a new method to an interface, you can just go ahead and implement the method right there inside the interface. Of course that won’t compile — you can’t have an implementation inside an interface (what do you think this is, Ruby?) — so ReSharper gives you the expected red squiggly. But it also gives you a red light bulb, and offers to move the method body into the implementing classes! (He has screenshots — scroll to the “Jedi Trick Level 3” section in his post.)
(Note: I haven’t had a chance to try this yet — it may only work in the upcoming ReSharper 3.0. Can anyone confirm whether this is available in current versions?)