Pole-sitting
I remember reading about this a while back, but unfortunately I can't remember where, and the precise details are more than a little fuzzy. What I retained is that a solar sail is key. The craft isn't really in orbit in a traditional sense, but rather poised above the pole in a position where the force on the angled sail balances the pull of gravity. It's somewhat analogous to an artificial LaGrange point. It might be more proper to call it hovering rather than orbiting.
I'm sure somebody will come along with better info, but that's a start.
--Robert