As far as the nicest things I've seen pilots do, one thing that stands out on Southwest is that deadheading crew, including First Officers and Captains, will more often than not help out with the passenger service duties, passing out peanuts/snacks and/or picking up trash (leaving the actual drink service to the on-duty FAs). It really gives you a good feeling about the airline when you see someone with four stripes on his shoulders and who's off the clock take the time to help out his fellow workers and the passengers by helping out with the snack service.