the californian company neurosky creates headsets that can read the users's mind. the headsets are called thinkgears and run on neurosky's eSense software.
the electrodes of standard medical electroencephalography [eeg] use a conductive gel to facilitate the reading of the signals. the thinkgear works with dry-active sensor technology and does not need such a gel.
more neurosky videos. another brain-computer interface.