Neurology has advanced to the point where an EEG can now be used to answer yes or no questions, reports Discovery news. And this could be used for good or evil.
For good, it can be used to communicate with vegetative people. If they have enough brainpower left to understand you, you can put them in an EEG and ask questions. They're not conscious enough to answer you, but their brain activates in particular patterns when imagining answering the question, which we can now read. And this proves that people who have been unconscious for years can still recover: their brain still works.
For evil, I imagine that this may be used for coercive interviewing. The evil spy, government, or whoever, crams you into an EEG and starts answering questions of you. And you don't really have to answer him with words, your own brain will give you away. (Unless, of course, you've decided to rehearse your lies ahead of time.)