Re: The Curator.... Who is he? (SPOILERS for "The Day of the Doctor")
11 winks at him, it's pretty clear that he's the Doctor who has finally settled down and retired. I like the idea of him being the last Doctor.
He could also be Tom Baker who wandered onto the set and began speaking to Matt Smith who was on break.
"Libertarianism is a good idea on paper, until you look at it."
Greg Proops, The Smartest Man in the World