Plenty of human-gadget interfaces can let you control a robot or a computer with your mind. An EEG-based affective computing system allows you tocommunicate your emotions, adding a new layer to human-computer interactions. In the video below, Robert Oschler of Android Review demonstrates EmoRate, a software program that catalogs his emotions. The computer tracks four primary emotions --  happiness, sadness, anger and fear -- and catalogs when they occur.