Here are mine:
• fly at sleep time if possible
• bring home baked cookies and packets of earplugs and offer them to your neighbours on the flight - seriously, it will make everyone so forgiving because they will know you have considered them.
• favourite books rather than new ones
• finger puppets
• ask the Dr for a medication to help him sleep - this is the only time I would advocate this
• spare t-shirts for all of you, plus an empty plastic carrier bag for dirty laundry in case of an incident, in hand luggage in case he gets sick on take off or landing
• chamomilla teething tablets can sometimes also help with general grumpiness
• do what you can to get bulkhead seats - you get extra space AND fewer neighbours to upset
• if he doesn't have a bottle or pacifier, sucking a lollipop can help with ear pressure