Assuming that you have successfully solved the problem of the AI covering the world with question-askers and that sort of thing:
"How do we write a friendly AI?" would be an important question, if you could trust the answer.
"What could we do that would make it safer for us to operate you?"
"What should we do to start a business that makes lots of money quickly, but doesn't draw peoples' attention to the fact that we have an Oracle AI?" could be useful.
"What are the top risks to the human race in near future? What should we do to reduce them?"
Revolutionize protein synthesis and cure various diseases if you have time to kill.
You ought to ask for not only answers, but evidence. if the goal is provable-friendliness, ask for the proof. In both English and machine-checkable variants.
The Future of Humanity Institute wants to pick the brains of the less wrongers :-)
Do you have suggestions for safe questions to ask an Oracle? Interpret the question as narrowly or broadly as you want; new or unusual ideas especially welcome.