I notice, looking at pictures of various light singles, that the tail number of the aircraft is typically prominently displayed somewhere towards the top of the instrument panel. If it were your own plane, you would quickly memorize it given the dozens of times per flight you have to give your callsign, but it's still useful for new pilots, rentals and trainers.
That led me to wonder: are the tail numbers of commercial aircrafts also posted in the cockpit, or is it omitted because commercial airliners more often use their company and flight number as their callsign, while the equipment used for a flight can change every time? I don't see any registration number label in this shot of a 737 cockpit, for instance, but it could be on the overhead panel obscured in this shot.