VivoMetrics has created a vest that records the movements of the wearer. It is currently being used to monitor the behavior of schizophrenics and manic-depressive patients, but could easily be applied to BCI. Something like this could be used as a failsafe for freely roaming patients, possibly as a way to signify the need to recalibrate or rebuild filters. Earth shattering? Nah. But worth a mention.