I'd probably send a huge percentage of it (up to $400mil) to a variety of my favorite organizations and efforts. And a pretty good amount to debunk HSUS. I'm not a crazy humble person or anything, but seriously, wth would I do with $500mil?!?! From there, I'd probably blow a few million, get myself a dream home and fully furnish it, and then invest the rest in schooling for me and my hypothetical descendants.