AaronSW may have left everything to Givewell, an efficient meta-charity
* http://www.givewell.org/
In this age of famous tech names donating millions or billions to charity, it may surprise you to realize that many of us consider these donations to be missed opportunities in terms of how much good could have been accomplished for the same amount of money, given more quantitative ways of evaluating the good done by a charity. Givewell is the leader in this form of evaluation and makes an extremely credible claim to be able to identify charities that use well-analyzed methods to achieve literally orders of magnitude more good per dollar than the usual suspects. There is no efficient market in utilons, but Givewell is trying to create one.
By giving to Givewell itself, Aaron Swartz's final legacy may be expected to accomplish far more good in the world than less carefully chosen gifts involving hundreds of millions of dollars.
I am not myself employed by or otherwise involved with Givewell, and my opinions and phrasing of the above have not been seen or approved by Givewell.