Ooh, my favorite. I am always looking up new ideas, being an amateur roleplayer and BDSM paramour.
Here are just a few I've either tried, thought about or heard about that seem interesting.
1. Boss and employee (Boss is the dom)
2. Cheating housewife and handyman (she's the aggressor)
3. Masseuse and client (she just surprises him with an oiled handjob)
4. Mile high club (guy asks flight attendant to go with him)
5. Doctor and patient (Doctor is the dom)
6. Interrogation (Cop has power over the suspect, or even better CIA and Russian spy, because then there's no rules!)
7. Teacher seduces student (either male or female can have the power)
8. Cosplay as someone from another country and do the accent
9. Sex worker and john - either a stripper or streetwalker negotiating price
10. Cheerleader and football player on prom night