It's important to give back, especially to good causes, charities and those who might be less fortunate. "Give freely, even as you have been given freely," is one of my favorite Biblical sayings. It means that God gives freely to us all the time, and we can be more like God when we act like this with others.
There are plenty of great causes that I try to give to regularly. lately, I've been using the services of Wikipedia so often that I finally made a donation. Here's the link if you want to donate too.