(Editor's note: Come to think of it, I don't know whether or not this qualifies as a "cool thing" since it could so obviously be misused, but still -- we don't have to like science, but we have to respect it.)
From the New Scientist:
Last week at the Society for Neuroscience meeting in Chicago, Jack Gallant, a leading "neural decoder" at the University of California, Berkeley, presented one of the field's most impressive results yet. He and colleague Shinji Nishimoto showed that they could create a crude reproduction of a movie clip that someone was watching just by viewing their brain activity.
The project is described in more detail:
Nishimoto and Gallant started their most recent experiment by showing two lab members 2 hours of video clips culled from DVD trailers, while scanning their brains. A computer program then mapped different patterns of activity in the visual cortex to different visual aspects of the movies such as shape, colour and movement. The program was then fed over 200 days' worth of YouTube clips, and used the mappings it had gathered from the DVD trailers to predict the brain activity that each YouTube clip would produce in the viewers.
The story says that other neuroscientists raised flags that "neural decoding" could be used to read memories and future plans. If I had to guess, I'd say that today's "cool thing" is probably tomorrow's annoying advertising-optimization technology.