Harmon Technologies, Inc.

Pitot heat - this keeps the outside sensor that drives the altimeter and airspeed indicators warm to prevent errors that might occur due to ice blockage.

Rotating beacon - This is the flashing red light on the tail.  This light is normally on whenever the aircraft is alive (i.e. the engine is or is about to be running).

Landing lights - a main landing light in the nose and additional taxi lights on the wingtips provide illumination at night.  These are normally off during cruise operation.  On the ground (even during the day), the landing light is turned on when cleared for takeoff as an addition indication to the tower and other aircraft that the plane is about to roll for takeoff.  It is normally left on when in the airport area below about a thousand feet.

Fuel Pump - The main fuel pump is an engine driven pump similar to that in most cars.  To provide even greater reliability, there is an electric backup pump that can be turned on by the pilot. It is normally left on during take off and landing so that the engine will operate normally even if the primary pump fails. 

Panel lights (and intensity control) for night operation

Master - This two part red switch is the main electrical switch for the airplane.  Since the engine does not require electrical power, the engine would keep running if this switch is turned off.  The second part of the switch allows the alternator to be taken off-line in the event that it malfunctions and starts producing too much voltage.  Turning this switch off powers down all airplane electrical equipment. turning it off when the airplane is shutdown makes sure that nothing runs down the battery when the airplane is unattended.