In my supervisory skills classes, we're told to get past experiences to predict future actions...which would be especially fun in this sort of situation:

"Describe a time your limit was pushed, and how you handled it"
"Tell me about your best sexual experience ever, and your worst; and why"

If you need actual interview questions though, a couple that have worked VERY well for me:

"Describe the best and worst jobs you've ever had, and why": gets people to actually TALK about themselves, first, and it's a good tool to compare those "why's" to the position they want. It also gives a good opportunity to see how the person reacts to past jobs: if they just spout horrid things, they probably won't be happy here, either.

"In your last positions, how have you left your employer better off than when you arrived?": I don't want someone who's just there to maintain...I want a person who's looking to improve things. A good way to test if people are REALLY "proactive, motivated, and show initiative". Sadly few actually ARE.