Via Bruce Schneier, interesting research into how to use mouse movements to detect lying:
Cognitive psychologists and neuroscientists have long noted a big "tell" in human behavior: Crafting a lie takes more mental work than telling the truth. So one way to spot lies is to check someone's reaction time.
If they're telling a lie, they'll respond fractionally more slowly than if they're telling the truth. Similarly, if you're asked to elaborate on your lie, you have to think for a second to generate new, additional lies. "You're from Texas, eh? What city? What neighborhood in that city?" You can craft those lies on the fly, but it takes a bit more mental effort, resulting in micro hesitations.
In essence, the scientists wanted to see whether they could detect -- in the mouse movements -- the hesitation of someone concocting a lie.
Turns out ... they could. The truth-tellers moved the mouse quickly and precisely to the true answer. The folks who were lying jiggered around the screen for a bit, in a sort of hemming-and-hawing adaptation of Fitts' Law.
That's kind of cool. And kind of scary.