I have just come back from seeing this movie, starring Helen Hunt, Kevin Spacey and that kid from the Sixth Sense (sorry, can't remember his name).
I highly recommend it. The basis of the story is that if someone does something good for you, you have to "pay forward" that goodness by doing something good for three other people. Those three people then each have to do good for three more people. And so forth.
It's a great movie, with a storyline that will draw you in, and compelling acting that will inspire you. Oh, and take a few tissues. Don't say I didn't warn you.