Mind control is both the GM's best ally and worst nightmare. Used against the PCs, you can get them to do whatever you want or, more to the point, not do whatever you don't want them to do.

But whatever you do, make sure this power doesn't fall into the hands of the players.

Aaaiiiieeeee!!!

Transcript

R2-D2: All right, Sally, I've been thinking about this.
C-3PO: I'm listening. This had better be heartfelt.
R2-D2: You'll love it. It's the perfect escape plan.
C-3PO: <sigh>
R2-D2: This hold is magnetically sealed, so we need a narrowcast scan, which I can perform using parts from these mining droids, and—
GM: You can't do that. You have a restraining bolt on you.
R2-D2: Restraining bolt? How does that work?
GM: The Jawas stuck it on your chassis.
R2-D2: Simple, I remove it with—
GM: No. You don't want to.
R2-D2: What? Yes I do.
GM: You can feel its influence flowing through you. It controls your actions.
R2-D2: Hmm. Okay, Threepio, can you just reach over and—
GM: You don't feel like finishing that sentence.
R2-D2: Man! This sucks!!
GM: Actually, you think it's awesome.