A librarian. Yes, I know, much of what you need is available online and your staff Googles with the best of them. Still, corporate librarians operate with a level of nuance and finesse that technology can't match. They can uncover sources so obscure as to be practically nonexistent. And they know what's what--they not only tell people what is known but also warn them what isn't. Something about Linus' warm blanket from the comic strip Peanuts comes to mind!
(þ: Nancy White)