I would do a lot of good.
Spread the wealth, help the poor, and do my best to subvert the system. Fund political and media organizations. Also, create community centers with an emphasis on civics.
Fund and establish autonomous non-profit social centres.
I'd also set some money aside for myself so that I can spend some time educating myself on progressive- and anarchism-based education (you know, the ones based on the ideas of people like John Dewey and Francisco Ferrer).
Then I'd use the money to set up a global confederated network of schools and collectives based on these principles.
I - along with thousands of other agitators will begin educating kids on the ideals of anarchism and thus begin the necessary process required to create an anarchist revolution. It took the Spaniards about 70 years to collectively educate themselves and create the Spanish Revolution of 1936. I'm guessing that, assuming I start tomorrow, a spontaneous global revolution can happen in the year 2080 or somewhere near that time.
I'd also buy a huge chunk of land, pretty much an entire valley. Set up wind & solar generation facilities to power more than my max expected energy demands and tap into the local aquifer if possible, with a wind-powered pump & huge holding tanks near the top of the ridge.
Then I'd build what would basically be a huge underground bunker complex of a house further down the hill. Water storage uphill would provide plenty of operating pressure, and I'd have one of the tanks have a large exposed black surface to provide solar heating of water to cut down on energy needs there.
Then I'd build some glass domes for greenhouses, a very well-equipped kitchen, and dormitories (all part of the same underground complex, except for the domes of course). I'd also build a fucking huge shop, equipped with all of the tools I could ever see needing.
The valley would have a basic airstrip, woodlot, etc. Then I'd invite all of my friends to live there with me, and have an open door policy for anyone that wanted to visit. Guests would be allowed to come and go as they want, as well as make use of the shop, library, etc.
Any money after that would be set up in a trust to provide operating & unexpected expenses in the future. Any further money after that would likely be invested in either setting up identical operations elsewhere or perhaps in a number of charities, or possibly starting my own.
In essence, I guess, I'd be setting up a self-sufficient commune of a sorts.