I think I would categorize stuff like opening doors for people under being polite, not generosity. And I usually try to hold the door for anyone. Do any of you remember seeing some commercial about being polite? One person would help another, and then the person that was helped would help someone else and so on. I kind of believe that if you are polite to someone you can make their day. Although, there are times that I say screw it. I guess it depends on my mood.
With my friends and family, we tend to pay for each other here and there. As for complete strangers, I don't see the point in giving to someone I don't know (unless it is something along the lines of a charity of sorts).
And getting a check for $100 from the Government? I would probably just use it for daily life (bills, food, etc.).