Transcranial Magnetic Stimulation is a technique in which scientists can alter your brain's electrical activity by subjecting it to strong magnetic fields. According to the article, there are a lot of potentially interesting medical and military applications. Of course, scientists need to be careful with these machines given that they generate "up to a whopping 3,000 volts and produce peak currents of up to 8,000 amps - powers similar to those of a small nuclear reactor." (Via Boing Boing.)