Mojoey has a nice, short story on his site about how easy it can be to be generous and what that generosity can do for others:
When he knocked on my door to ask for a loan, he said he needed cash to get across town to visit a free clinic. I gave him everything in my wallet after initially saying no. He pleaded with me, which was out of character. He was having trouble with his eyes, it was important that he see a doctor. $26 did not seem like a lot of money to me, but it meant a lot to him. He promised to repay me despite my assurance there was no need. I did not expect to see the money. I was surprised by what happened next.
(via Deep Thoughts)