Adjusted Aggregate Wealth

Quick thought: when calculating the world's richest people, magazines (or whoever) should make the list based on (current wealth) + (aggregate money donated to charity so far). No double counting, of course—if you've pledged a bunch to charity, it only counts once. Anyway this gets the incentives right, to the extent rich people care about their rankings (and I think some of them care a lot). They can go ahead and give a bunch of money away without jeopardizing their place on the list.

You could even do it like this:

(wealth for purposes of list) = (current wealth) + (present value of aggregate money donated to charity)

So in other words, if you gave $1 billion to charity 10 years ago, in the formula it would count as like $1.1 billion or $1.2 billion or something like that, reflecting foregone interest.

Maybe they already do this and I'm just a dumbass.