Post-Microsoft Bill Gates is a much more interesting person. I'm not a Microsoft fan, but I have a huge amount of respect for how he's choosing to spend the money he made. Interesting contrast to Larry Ellison, for example.
Larry Ellison has put virtually all of his assets into a trust with the intent of giving away 95% of his money to charitable causes when he dies.
http://cms.givingpledge.org/#larry_ellison
The full letter is an interesting read