Great thread!
Myself and my boys, now 4 and 6, routinely hold doors and give up seats, but this is common courtesy and expected behavior from civilized gentlemen.
We have given away fast passes and seen the delight on faces when their wait time was cut from 4 hours to 0 minutes.
We have taken other children on rides when their parents couldn't or wouldn't.
The best thing, though, I think was Dec. 2001. Our entire family went and we were going to stay a couple of additional days and had bought tickets to
MVMCP. Some of our family had to leave early, so we decided to leave with them. On our last day, we remembered the tickets, and saw a family of three (only needed three tickets as youngest was only 2 1/2) discussing things to do etc. We talked to them briefly, and gave them the tickets to MVMCP. They, in return, sent us a lovely thank you note and Christmas ornament telling us how much they enjoyed it. That made our Christmas that year!
HAPPY HOLIDAYS, EVERYONE!