Real-world use for a function returning a pointer to a class data member?

A friend of mine - a computer engineer working in the industry - IM'd me today with some questions about some code he was working with. One thing he asked me about was a function that returns a pointer to a class data member. Now, I completely see the purpose of a pointer to a class member function, but the only uses I can imagine for a pointer to a class data member are completely artificial ones; I can't think of a real-world use for such a thing. So, anyone care to enlighten me? :-)

ETA: Maybe the terminology isn't as standard as I thought, or maybe it's just that the terminology is confusing, but to clarify: by a "pointer to a class data member," I mean an actual pointer-to-a-class-data-member type; the function is prototyped as something like A B::* f(), and its return value would be dereferenced using something like instance_of_B.*(f()). That is, it doesn't return a pointer to a data member of a specific instance of the class; rather, it returns a pointer to a data member of the class as a whole, and this pointer can be dereferenced using an instance of the class.

Thank you to everyone who's replied so far. :-)