When we call the GetListItems or GetListItemChanges methods in Sharepoint's Lists Web Service, we pass an XmlNode parameter specifying which fields we want to return, in this format:
This one was suggested by a coworker leery of accidental recursion. Too many people aren't used to thinking in terms of recursion and will miss a recursive call inside a method and accidently start an infinite loop, or miss the meaning of a method thinking it's an overload call.
I remember discovering C#'s null coalescing operator a while ago. I can't say I use it a lot, but it's useful to clean up my code when I do need it. However, there is another similar scenario that it doesn't cover: