A Lever Long Enough

Imagine this thought experiment:
You are the single richest person in the world, and the founder of the most influential software company in the history of mankind.
In 2000, you use your massive personal wealth to establish a powerful charity foundation, and continue to lead your company.
Then, in 2006 you have a vision, A powerful vision of how you could use your wealth to change the world in a meaningful and permanent way.
You recall the words of Archimedes, that given a lever long enough he could move the world, and you realize that you have in fact the largest economic lever ever to be in the hands of an individual.
You announce that you're leaving your day-to-day role at the company you founded in order to focus full-time on your charity organization.
You confidentially share your vision with your friend, who happens to be the second richest person in the world.
So striking is the vision that, 10 days after you announce you're stepping down, he announces that he is giving away the vast majority of his entire net worth, and that almost all of it will go to your charity orgainization.
The tool that you've built to change the world is now twice as strong, and you have the personal resources if need be to repeat that kind of contribution from your own bank account.
Never before has such wealth and ability been concentrated into the hands of a couple of individuals. What could be beyond their grasp?
What scope must their vision be, to casue the two wealthiest people in the world to bet their entire futures upon it?

These are the thoughts that occurred to me after Warren Buffet announced he was giving $31 billion dollars to the Bill & Melinda Gates Foundation, just a week and a half after Bill Gates announced he was phasing out his involvement with Microsoft to focus on the foundation full-time.
I don't know if this is how things happened or if so, what their vision might be, but my mind boggles at trying to concieve of a project that could consume such a vast amount of resources.

How would you change the world with $60 billion to spend and another $47 billion in your bank accounts?


Update: This webcomic from 1999 seems to have had similar thoughts.
A Suitable Seed