Paying it forward

Lately I have really been thinking about the concept of "pay it forward". It started when I went to eat at Ingrediant (mediocre BTW) and they asked that you not tip. Instead, they ask that you hold the door for someone, pet a dog, etc. That got me thinking about our sense of compensation as a society.

When someone buys me lunch, I feel obligated to pay the next time we go to lunch. When my neighbors let me have an egg so I can bake cupcakes (because I inevitably need something when I get the urge to bake) I always bring them some afterwards. I keep mental note of the things people do for me so that I can pay them back at some point. But what if instead of paying them back, I paid it forward? What if I donate Cash's swing (that he NEVER used) to his daycare instead of posting it on Craigslist? Or give my maternity clothes to one of my residents who just found out she is pregnant? What if I helped out someone else, someone who really needed it?

Would the person who bought me lunch feel snubbed? It would be rude of me to not do something to thank my neighbors for helping me out in a pinch. Should I pay it back AND forward? And can't we do things for people without there being some sort of scoreboard to see who is the nicer person?