16. A tangible computer-readable memory device storing instructions that, when executed on a processor of a computing device having a sensor, cause the computing device to perform actions associated with gestures performed by a user, by: transitioning to a training mode upon receiving. from the user, a training start request; during the training mode: while the user performs the gesture, monitoring the sensor to detect an identified sensor output identifying the gesture during a training period between the training start request and the training completion request; identifying, during the training, period, a restricted period that is shorter than the training period and during which the identified sensor output identifies the gesture; associating with the gesture the identified sensor output of the sensor during the restricted period; and associating an action with the gesture; transitioning to a recognition mode upon receiving, from the user, a training completion request; and during the recognition mode: monitoring the sensor output of the sensor; and upon detecting that the sensor output matches the identified sensor output associated with the gesture, performing the action associated with the gesture.
20. The tangible computer-readable memory device of claim 16 , wherein: the computing device comprises at least two sensors; the action is further associated with the sensor providing the identified sensor output that is associated with the gesture; and performing the action further comprises: upon detecting that the sensor output matches the identified sensor output associated with the gesture, performing the action associated with the gesture and with the sensor providing the sensor output.