In this paper, we identify four application areas where BCI assistive technology can have a real, measurable impact for people with motor disabilities; namely “Communication and Control”, “Motor Substitution”, “Entertainment”, and “Motor Recovery”. The remainder of the paper is organized as follows. The rest of this section is devoted to the research challenges currently faced by BCI-based assistive technology. Then, in Sections “Communication and Control”, “Motor Substitution”, “Entertainment”, and “Motor Recovery”, each application area is discussed, and the current state-of-the-art of each is reviewed. Finally, in Section “Summary”, we summarize the main message of this review paper.