[bhuga]

One general rule: avoid binary/rating questions. So not:

"Do you like working at X?"

This question has a "right answer" (yes), and you'll always get it. Instead:

"What's your least favorite thing about X?"

Phrase all of your questions as free-form responses instead of multiple choice. This is very helpful to get interviewers talking.

For specific questions, there's a lot of good ones on this thread, so the only specific question I'd add is this one, which I found very helpful for startups and fast-growing companies:

"It's 2 years from now, and X has failed. What happened?"

Well-run businesses had a well-understood answer about their biggest risks; poorly-run places had platitudes and "it could never happen."