Billionaire Givers

About 40 billionaires have signed on to "The Giving Pledge," a charitable initiative started by Warren Buffett and Bill and Melinda Gates. Each has made a commitment to give the majority of their wealth to the causes and charities of their choice.

Forbes estimates there are 403 billionaires in the U.S. Some, including a talk show host, haven't commented publicly on the pledge, and others, including a California gubernatorial candidate, reportedly have declined.

You don't have to be a billionaire - or even have money -- to help others. Here's how you can find volunteer opportunities in your area.