We’ve all seen the photo ops, heard the sound bites, and listened to the well meaning single du jour on the radio. But which celebrities are really serious about changing the world? Whether their philanthropic endeavors are high-profile or they pitch in quietly, away from the cameras, here are 20 celebs that make a difference:

One of the most interesting new features about the electorate that's coming into sharper focus during this campaign cycle is a certain sector's use of social networking technologies to achieve its collective social goals.

O Ambassadors™ is an exciting new joint project of Oprah’s Angel Network and Free The Children that will inspire young people to become active, compassionate and knowledgeable global citizens.

When Craig Kielburger first appeared on The Oprah Show in 1999, he was a 16-year-old social activist on a mission to show young people they have the power to change the world. Since that day, Oprah's Angel Network has teamed up with Craig's organization, Free The Children, and built almost 60 schools in underdeveloped countries around the world.

No TV, no video games, nowhere near home. Twelve teenagers are in for the adventure of a lifetime! Find out how your kids can become a part of O Ambassadors.

Instead of watching Twitter's ups and downs, we the members of the tech community could be using our social media super-powers to make a real difference in the world. We know how to spread news fast, share images and videos, organize our friends, and empower others all by using the same social media tools that we use in our every day lives. Isn't it time we put them to use towards a good cause? Below are some great examples as to how that can be done.