On GQ just recently, there were two questions of Baseball trivia which were almost instantly answered by zev_steinhardt. My immediate thought was, “if I’m ever on ‘Who Wants to be a Millionare’ and need help with a baseball question, I want him.”
My understanding is that you can have several friends lined up for different areas of expertise.
So…what Dopers would you want for “phone a friend” on a specific subject? What comes to mind immediately are Zev for baseball questions, and Eve if the subject involves old movies.