If you haven't already seen it, take a few minutes to look at Carnegie Mellon computer science professor's now famous "last lecture." Here's a man that is leaving life with elegance, courage and a sense of purpose. It's in the lives of "ordinary", extraordinary people that I'm finding the biggest sources of inspiration these days.
Another example: a friend of mine left a Wall Street position for military service after 9/11 because he thought it was the right thing to do. He completed his service and at the same time set up a charity called "Give to the World", which uses US troops to get basic supplies in to war torn areas where humanitarian organizations are unable to reach. This is worth checking out as well. My favorite quote from one of the founders is this: "Someone once said to me, 'you can’t save the world.' Hopefully one day, no one will ever believe a word of it."