Enter wefeedback.org.
It encourages people to 'feed back' their favourite food to someone who doesn't have it. What actually happens, though, is that you donate the cash value of that food, and end up giving 50 people (or however much that money can buy) a meal.The genius is that it shows you just how many people giving up that coffee can feed (Cost of one cheeseburger = 40 children fed), and then tracks the number of people that you've fed. Also, it encourages you to bring others into the scheme and add them to your 'network'. If you click the image, you should be able to see there that you can not only see how many people you've fed, but also how many people your network has fed. And, of course, it's got all sorts of options for linking this fact in with your social media.
There are a few other really nice things about this that I'll let you discover on your own. But essentially they've found a way to make it cool to feed people who're hungry. I think they've given themselves a decent chance to popularise philanthropy.
There's a cool video that explains it all better than this, but you only see it after you sign up and I can't find it on YouTube. I just signed up. Sign up, check it out, feed some kids.
Not sure how some Christians will react, not wanting to advertise how much they're giving and all, but I guess you just don't connect it up to your social networks then.
Anyways, here's a video I could find, but more on the general work of the World Food Program than on the We Feed Back project.